So what build is the most powerful for tanks.

That's an incredibly complicated questions because it has multiple answers. If your talking plain SO's and 'powerful' as in pure damage mitigation. Stone would take that spot hands down.

I was basing my comment about AAO's taunt effectiveness on experience playing with it.

I've witnessed other tanks gather a spawn up and just stand there, and the spawn will keep wailing on the tank, even while being attacked. I tested it while teamed with an Invuln tank. Using JUST the taunt aura (no Taunt, no use of Gauntlet) the Invuln was pulling agro off of me, and I could not pull it back to me.

AAO also seems to have a lower damage threshold for losing agro. In other words, a teammate won't need to deal as much damage to peel agro off of a Shield tank as they would a Stone tank.

I dunno, maybe I'm not slotting enough taunt durations in AAO, or am somehow using it wrong. What I DO know is that, thus far I seem to have to taunt a little more actively than other tanks I have teamed with to maintain agro control. I don't know why that is, and the numbers don't give any indication why, especially compared to Invincibility, because the numbers say they are the same, and AAO debuffs the enemy, while Invincibility does not. I have had Willpower scrappers pull agro off of my Shield tank, which, from what I understand, shouldn't be happening.

Is one taunt duration enhancement not enough for AAO? That's the only thing I can think of that would lead to the issue I'm having with it. I admit that it is possible that the power is fine and I'm just having trouble with it for some reason.

Shield Charge is a great taunt.

I have a Shield/SS tank and I have no problems holding aggro, foot stomp and shield charge seem to do the job. And if that truly isn't enough, Taunt works pretty darn well too.

Yeah, I've had zero issues on my Shield/WM. But I'm always attacking, so there's an extra variable. I've had to ease up on TF's when I was the lower-level off-tank to avoid stealing aggro from the main tank.

Might be worth mentioning that my tank is Shield/DM. I don't have a second high damage AoE power to use, and Shield Charge isn't up to use on every spawn.

My Shield/SS isn't high enough to be worth much yet, so that might change my opinion on AAO when he gets higher.

WP/SS is a powerhouse...in my opinion.

Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/

Click this DataLink to open the build!

Vitality: Level 50 Mutation Tanker
Primary Power Set: Willpower
Secondary Power Set: Super Strength
Power Pool: Fitness
Power Pool: Fighting
Power Pool: Leaping
Power Pool: Leadership
Ancillary Pool: Energy Mastery

Hero Profile:
Level 1: High Pain Tolerance -- Numna-Heal(A), Numna-Heal/EndRdx(3), Heal-I(3), Aegis-ResDam(5), Aegis-ResDam/EndRdx(5), S'fstPrt-ResDam/Def+(7)
Level 1: Jab -- Hectmb-Dam%(A), T'Death-Dam%(7), Mako-Dam%(9), Zinger-Dam%(9)
Level 2: Mind Over Body -- Aegis-ResDam(A), Aegis-ResDam/EndRdx(11), Aegis-ResDam/Rchg(11)
Level 4: Haymaker -- C'ngImp-Dmg/EndRdx(A), C'ngImp-Dmg/Rchg(13), C'ngImp-Acc/Dmg/Rchg(13), C'ngImp-Acc/Dmg/EndRdx(15), C'ngImp-Dmg/EndRdx/Rchg(15), RechRdx-I(17)
Level 6: Fast Healing -- Mrcl-Rcvry+(A), Mrcl-Heal(17), Numna-Regen/Rcvry+(19), Numna-Heal(19), RgnTis-Regen+(21), RgnTis-Heal/EndRdx(21)
Level 8: Indomitable Will -- LkGmblr-Rchg+(A), GftotA-Run+(50)
Level 10: Rise to the Challenge -- Numna-Heal(A), Numna-Heal/EndRdx(23), Numna-Heal/Rchg(23)
Level 12: Quick Recovery -- P'Shift-End%(A), P'Shift-EndMod/Acc(25), P'Shift-EndMod(25), P'Shift-EndMod/Rchg(27)
Level 14: Swift -- Run-I(A), Run-I(27), Run-I(29)
Level 16: Health -- Numna-Heal(A), Numna-Heal/EndRdx(29), Numna-Heal/Rchg(31)
Level 18: Heightened Senses -- LkGmblr-Rchg+(A), LkGmblr-Def(31), GftotA-Run+(31), GftotA-Def/EndRdx(33), Ksmt-ToHit+(50)
Level 20: Knockout Blow -- Hectmb-Dmg(A), Hectmb-Dmg/Rchg(33), Hectmb-Acc/Dmg/Rchg(33), Hectmb-Acc/Rchg(34), Hectmb-Dmg/EndRdx(34), RechRdx-I(34)
Level 22: Taunt -- Mocking-Rchg(A), Mocking-Taunt/Rchg(36)
Level 24: Boxing -- Empty(A)
Level 26: Tough -- Aegis-ResDam(A), Aegis-ResDam/EndRdx(36), Aegis-ResDam/Rchg(36)
Level 28: Weave -- LkGmblr-Rchg+(A), LkGmblr-Def(37), GftotA-Run+(37), GftotA-Def/EndRdx(50)
Level 30: Rage -- GSFC-ToHit(A), GSFC-ToHit/Rchg(37), GSFC-ToHit/Rchg/EndRdx(39), GSFC-Rchg/EndRdx(39), GSFC-ToHit/EndRdx(39), GSFC-Build%(40)
Level 32: Combat Jumping -- LkGmblr-Rchg+(A), LkGmblr-Def(40), GftotA-Run+(48)
Level 35: Stamina -- P'Shift-End%(A), P'Shift-EndMod/Acc(40), P'Shift-EndMod(42), P'Shift-EndMod/Rchg(42)
Level 38: Foot Stomp -- Armgdn-Dmg(A), Armgdn-Dmg/Rchg(42), Armgdn-Acc/Dmg/Rchg(43), Armgdn-Acc/Rchg(43), Armgdn-Dmg/EndRdx(43), EndRdx-I(45)
Level 41: Maneuvers -- LkGmblr-Rchg+(A), LkGmblr-Def(45), GftotA-Run+(45), GftotA-Def/EndRdx(48)
Level 44: Focused Accuracy -- GSFC-ToHit/EndRdx(A), GSFC-Rchg/EndRdx(46)
Level 47: Strength of Will -- Aegis-ResDam(A), Aegis-ResDam/EndRdx(48)
Level 49: Super Jump -- Jump-I(A)
------------
Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Run-I(A), Run-I(46), Run-I(46)
Level 2: Rest -- Empty(A)
Level 1: Gauntlet

I've played the game since I-1, and have a long and extensive list of lvl 50 tanks as they're my favorite AT:

Fire / Fire (1st)
Fire/ Stone (2nd)
Invul / Mace
Invul / SS
Ice / Axe
Stone / NRG
WP / Fire
Dark / Fire
Shield / SS

Out of all the tanks, the stone tank by far has the best defense, the invul tank can suck up aggro like no other, the fire back when burn was worth a damn ruled the game. Ice has nice secondary affects, shield with SS has great dmg and dark works wonders with mobs but sucks on bosses.

If I'm building a no crap, take no prisoners, machine of destruction then I'm going with the Stone / NRG...practically indestructible, running mudpots for some xtra dmg, an early PBAOE attack to winnow out the mobs and then the big gun single target attacks to lay low the bosses. This tank won't suck up massive amounts of aggro, though mudpots gets their attention but lays waste to the mobs and stacks up the body count.

However, I'm now more of a scrapper type player and I will say that I love my claws / sr, dm / sr and db / sr.

My Fire/Stone tank massacred all the Faultline EB's pre-SO's. My Inv/SS is specced out as a ranged damage dealer just for kicks and does quite well at it. Tanks can do a great many awesome things, they just bloom late in the game.

Toughest tanker I've ever played: Inv/DM. It kinda feels like cheating, and he doesn't even have IO's yet.