I'm going to do each section in little parts, starting with the HQ's and then working my way down. As I typically write my articles on the fly and then go back to edit them later to add/subtract stuff, I don't know how much will be mentioned for each unit. We'll see as time goes on. Feel free to pipe in! You might bring up something I missed or forgot about, so then I'll be able to have a more complete analysis. :)
High Marshal Helbrecht:
I talk in great length about Helbrecht in this email response post, but I'll highlight some of that here. To begin, he's a very hefty price-tag at 175 points. Because we'll commonly reach those points levels with our HQs in 6th Edition, I should clarify my statement a little: for what you get, he's far too expensive. This trait becomes even more exuberant when taking a Command squad, due to the requirement of taking the Furious Charge trait for every member. Which, in my opinion, is no longer worth the cost due to losing the +1 initiative.
He does have artificer armor, which will be incredibly important in 6th Edition. This will prevent the majority of power weapons from hurting him. But his 4+ invulnerable save leaves me feeling unsafe, especially with the addition of Precision Shots and Challenges to the game. Add in the huge amounts of Force weaponry that is around and it gets a little scary. The lack of Eternal Warrior really hurts Helbrecht in this respect, though "Look Out Sir!" will help mitigate that a little bit. Still, I'd be more comfortable with a better invulnerable save at least. The Sword of Marshals is pretty nice when it works out, but its still only AP3. The only other notable piece of wargear he has is the Combi-Melta, which is situational, but nice to have nonetheless.
Other than that, his stat-line is pretty average for a 4th Edition commander. However, his Rites of Battle really don't give us much anymore, as the only thing its really going to help with is Righteous Zeal. Kill Them All is gone, so we no longer need that LD10 across the board.
In summary, you'll probably want to avoid using Helbrecht because he can't do some of the cool things our other basic Commanders can do (like take bikes), for similar points. ;)
Unlike Helbrecht, I believe Grimaldus might be seeing a minor revival of sorts in 6th Edition. However, not on a full scale level, as he still has problems. He too is really expensive. Clocking in at 195 points, he's nothing to sniff at. But...but...but! You are taking high priced Chaplains, why not take Grimaldus instead?
The problem lies in his equipment. With the change to the Crozius Arcanum (being a power maul), he's no longer a MEQ killer. And that is going to be your main opponent. Having +2 Strength doesn't make up for the fact that they get armor saves against it. Just like in the previous edition, we need to kill what we charge and losing the ability to negate 3+ armor is huge.
What he does do, however, is kill everything else REALLY well. Instant Death on T3 models is nice, so its not a total loss. Likewise, he's equipped with a Master-Crafted Plasma Pistol which is kinda whatever. The lack of a 2+ armor save really hurts though and will ensure Grimaldus takes far more wounds than he needs to. Challenges will destroy Grimaldus, as he's got nothing to protect himself with.
However, not all is lost. You don't entirely take an HQ choice based on his stat-line and wargear, but also his special rules. This is where Grimaldus has some interesting ones. His servitors have a Holy Relic, so he has the capability of launching some devastating charges when combined with our "new" AAC vow. Likewise, you can also use it when you get charged to give you some extra attacks. Grimaldus also has a ghetto Eternal Warrior in "Only in Death does Duty End". But even there, if he fails the test or takes another wound, he dies. You get one safety net save and that's it. In addition, his Unmatched Zeal special rule has a 6" bubble so if you're running a footslogging list, you don't have to worry about Righteous Zeal (as the wording is still ambiguous).
In the end, 195 points for someone without T5, 2+ armor, and/or proper wargear still isn't worth it. We can do the almost the same thing with a normal Chaplain, but cheaper and more effectively.
The Emperor's Champion:
The EC is a requisite in every list 750 points or over, so he's the one I'll start with. Vows are the most obvious place to start here, as they are the force multiplier of the Black Templars army. They also influence how many points he costs you. Depending on how you look at it, the changes to some of the vows when 6th Edition hit could be considered good or bad. Long story short, "Accept Any Challenge" was changed from Preferred Enemy to the new Rage special rule. Honestly, I expected to lose PE when our codex was updated, so this wasn't a big shocker to me. But to other people? Watch out, cause the sky is falling. I don't believe it is and I discussed why in this post.
"Abhor the Witch" was the other vow changed slightly, but not to change its function. It still works the same, but until an updated FAQ changes things, we get two "saves" against psychic powers. First the "Abhor" save, when an opponent first targets your unit. Then, if you fail your save and they pass their psychic test, then you get the Deny the Witch save too. Works out to be something like a 44% chance to nullify a power used against you. Which is a pretty high percentage. And that isn't even counting the free consolidation move you get at the beginning of the game verses armies with psykers.
Outside of vows, he's still a beast. Higher WS skill than anything in our codex, plus has a LD 10 for any squad you'd like to toss him in. The Black Sword changed a little bit, giving it only a AP3 value in close combat, but it still has the +2 Str. So while he'll still kill MEQ just fine, its the 2+ armor saves that will give him trouble. Our EC has a 2+ armor save (which is huge) and also has a 4+ invulnerable save in close combat. So he's got a reasonable amount of durability as well.
In addition, he is required to take and receive any challenge in the combat he's in. Making him deadly to any opponent who doesn't have 2+ armor (Eldar/Dark Eldar, I'm looking at you). No "Look out sir!" saves in a challenge. In the end, even though he's required, he's an excellent HQ.
Right out of the box, the changes in 6th Edition requiring a Warlord means that we either have to take a Commander or a Chaplain. If you want cheap, a Commander will save you some points over the Chaplain. But you lose the re-rolls on the charge that a Chaplain gives you. "Rites of Battle" is much less important now, due to the removal of "Kill the All". Nevertheless, with a decent stat-line and access to everything in the BT armory, you can create a monster character.
He is an extremely versatile and can be outfitted in any number of ways to compliment your forces. I would outfit him a CC-role, however, as that is one of the places he excels. Storm Shields are a must, as well as any sort of 2+ save if its possible. Challenges will keep him busy and you have to be able to survive them, while being able to take out your opponent. There is also the option to take either a Command squad or a Terminator Command squad to accompany him, which also add their own dimensions to the battle.
Where he really comes into his own is when you give a Marshal a Space Marine bike. With the changes to bikes, these become extremely durable and essentially give them Instant Death protection from high strength weaponry. If you also invest in artificer armor and a storm shield, he'll be extremely difficult for your opponent to kill. Use his mobility to assault the flanks of your opponent's army, or to find the weak points and wreck havoc. You ideally want to give him a power fist or thunder hammer, but a power axe will be sufficient as well. The key is the AP2, but the ability to damage tanks and monstrous creatures consistently is important. His durability will compensate for the I1 strikes.
Overall, he is best suited for a close combat role for your forces if you need a cheaper HQ. If you have another CC-unit in the army, the Chaplain might be a better choice due to the Litanies of Hate.
What was lost, is now found! I "predicted" several months ago that Chaplains would be making a huge revival with 6th Edition. No one believed me. Now Chaplains are being taken in almost every BT list out there, and for good reason! With the changes to "Accept Any Challenge", close combat units need a way to ensure that maximum damage is inflicted. Preferred Enemy was huge in helping to create a torrent of attacks on an opponent, but it made the Chaplain irrelevant. Now that its Rage, an extra attack doesn't stack up quite as well. Unless, of course, you add a Chaplain to their squad. Litanies of Hate will make your opponent cry. However, just like Rage, it relies on the charge. So it will be instrumental that you learn how to set up your charges properly with your list.
On the other hand, if you're not going to combo your Chaplain with a CC-oriented unit of some sort, then it might not be worth taking him (depending on your build). A cheaper Commander might be the better option. In either case, due to Challenges, I think the Master of Sanctity is the required purchase here. I just don't trust the survivability of 2 wounds anymore. The things Characters can do now just isn't worth the risk! You want to be able to keep your HQ alive as long as possible so he continues to buff his squad.
Just like the Commander, 2+ armor is almost a requirement. The storm shield is less so, as he has a built in 4++ save, but if you want to play it safe (I'd suggest it), its a good purchase. However, before any other purchase is made, a power fist needs to be taken. This will give you the high Str, AP2 weapon you need in your list, as well giving you versatility of choice when combined with the Crozius Arcanum. Doing as such will help ensure you win any challenges directed your way.
Chaplains also do extremely well on bikes, just like the Marshal, so don't hesitate to explore this option. But the jump pack is an upgrade that quite possibly opens up another facet of our outdated Codex -- the Assault Marines. By giving these guys re-rolls to hit on the charge (with AAC and Hammer of Wrath), they are actually not half bad. They are still susceptible to torrent-of-fire, but you don't have to invest much into this squad to make them extremely annoying to your opponent. In the end, this is an excellent HQ choice for the majority of the Black Templar archetypes in 6th Edition. If you're planning on fielding a close combat squad in your army, he's going to be an necessary purchase.
Ah, yes. The humble Command squad. There isn't a whole lot of reasons to take these guys anymore, other than to take a theoretical (assuming the Drop Pods are fixed) first strike-melta unit into your opponent's deployment zone. However, with Feel No Pain being slightly nerfed, they won't be as survivable. Nevertheless, you can make a nasty squad out of these guys. They are one of the few places you can take dual-melta and multiple power weapons, but they are harder to deliver with the changes to transports. This squad can quickly become expensive, but is a versatile tool in the box for the right army.
Terminator Command Squad:
Because of the changes to Cyclone Missile Launchers, combined with the Tank-Hunter rules, this unit became extremely popular in 5th Edition due to being able to take two heavy weapons per squad. With the new version of Tank-Hunters, Assault Cannons have become an interesting option once again. Re-rolling the armor penetration dice gives you a much better chance to "proc" a rending roll. Which is excellent, especially when you consider the addition of Flyers to the game. Of course, CML's are the gold standard if you need reliable long range support for your army. They will shred Rhino-chassis with ease. This squad gives you plenty of AT/AI for its price tag.
If you want a more close combat-oriented squad, a Chaplain will be a nice HQ for you. Toss in those ACs and you've got a mid/close-range squad that is packing the nasty. Alternatively, the Commander provides a cheaper way to bring in those TH weaponry to the board while giving you some "Oomph" in close combat. This squad is the only way to unlock the "Blackwing" archetype (4-5 Terminator squads) for us. While not entirely balanced, such an army can be extremely difficult to beat if not prepared for it. This unit is a great alternative to the Terminator squads in the Elites slot.
Well, there you have it. My review of our HQ units. I believe I touched on a little bit of everything, without going so deep into the details to make this a 900 page essay. I'd prefer to keep your eyes from bleeding. Did I miss something or have comments on what is written? Let me know! :D