Tier 1 (Can drag a team kicking and screaming to the enemy's core)
New Patch, new opops. So just to recap, I look at pick potential, solo threat, and teamfight impact as the main determiners of tiers.
Garrosh: Unsurprisingly, still at the top for now, but people have slowly learned a bit how play against him. Maybe in a few patches, I can remove him from the top, but for now, he's still king. Garrosh requires almost no coordination from his team to make pickoffs, making him invaluable in hl.
Muradin: Since his rework, Muradin is probably one of/if not the strongest tank in the game. His early pick potential is enormous, he's super safe to make plays on, and his damage allows him to threaten backliners by himself. Even with the heavy impact stun nerf, the character just feels overtuned, and I love every bit of it.
Tier 2 (Still strong options but require team coordination)
ETC: Probably the second strongest tank in the game after Muradin, but is unfortunately too team reliant to be a perfect HL carry tank. Good ETC's can do work, but his lack of solo pressure makes him require at least somewhat competent teammates (or a 5 man mosh.) Still, ETC is flexible and strong in almost every category so he's definitely a great tank to run with and is rarely first banned.
Tyrael: Maybe this is just me, but I've found Tyrael to be super good in HL of late, and have completely reversed my opinion of him as an HL carry tank. He doesn't have hard CC, but he waveclears, lanes, and threatens backliners better than almost any other tank, allowing him to fill in some holes in your team comp. Add to this that Sanctification is a game winning ult when used right and his boss control post 16 is unparalleled and you've got a great hero to carry with. He plays differently than other tanks early, but I think his strengths completely outweigh his lack of hard cc.
Tier 3 (Situational carries and the outclassed)
Diablo: I've said this many times, in the right circumstances (small map where he can get souls easily) and into a low damage comp, Diablo is god tier. He remains in this niche, but Muradin's ascendance has just thrown him back a bit.
Johanna: Joh has always had trouble carrying HL. Her waveclear and safety is nice, especially for players who are not as comfortable in the role, and her update has definitely made her more of a playmaker, but she just is outclassed by tanks in the tier above. He lack of ability to hard engage reliably just hurts her too much as a cc tank, and she doesn't offer enough in other categories to make up for it like Tyrael.
Anub'arak: With Muradin rising, Anub regains his position as the third best stun tank. There is very little reason to pick him over Muradin or ETC right now if they're up, so he fills a slot only when they're banned. He can still carry with good picks and smart Cocoon usage, but his low health pool just hurts him too much is sustained fights.
Arthas: I've been memed so much for putting Arthas is top tier last list, and I still think he deserved it then. That being said, he definitely does not deserve that spot now. Arthas as a main tank is easy to play, but like Diablo, he is only really able to bring out his true hypercarry nature in the right situations. When the enemy picks Valla, Cassia, or Greymane as a main dps with low damage otherwise is when Arthas can really shine. His ability to shut down these carries while controlling a team fight is unparalled and he can certainly carry late game team fights when played correctly.
Tier 4 (But y tho?)
Stitches: Probably gonna get a lot of flack for this, but I think Stitches is not a reliable HL carry right now. Getting kills off of raw hooks requires more coordination then you'll find in a standard HL game and he just doesn't have the impact outside of hook early to justify the pick. Post 16, he becomes super strong, and good hook->gorge plays can definitely swing a game, but I find these strengths to be too sparse to justify his lack of impact early in most games.
Varian: Speaking of lack of impact early, there's Varian. Not being a hero until level 10 hurts, and his taunt just isn't good enough post 10 to justify the pick. Varian's only really claim to fame is not dying, and you really want more from your tank than protected btw. Blizz, pls rework this hero already.
Tier 5 (These are not tanks. Stop picking them in the tank role)
These characters are not main tanks and should not be picked in this slot. They cannot properly peel/engage for their team. They are fine picks overall, but do not qualify as a "main tank" and should be picked as another role.