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One nice advantage of chainmail is the later levels of masterwork can bump Will, which won't be all that great for most barbars.

I wonder what the best AC a hybrid Barb could get with BCL, dumping dex and grabbing plate and plate spec. Barbarian in plate with a free +2 (shield bonus) wielding an executioner axe = awesome.

A little slow, but awesome. Even if you stick to Dex secondary and use fullblades for the mastery, ignoring Scale and sticking to Hide, that could work pretty well to maintain your speed 6.

STR/CON

AC is overrated. Hitpoints and temp hitpoints are where the barbarian does defense. If you set it up right, you can get 20 temp hitpoints every time you kill something. Plus, if you're a minotaur you get a free attack every time you get close to dieing. How cool is that. Just make sure the cleric can get you up afterwards.

I ran a Thaneborn barbarian using heavy armor for awhile, and I was happy with the amount of Cha I could pump, even if it cost a few feats and ran my reflex into the ground.  But cha-based riders for barbarians seem to frequently do more than con-based ones (usually applying attack bonuses/penalties or defense penalties, sometimes extra damage), and high cha was both part of my character concept and important in my party, since I had to be the face.  If I were making a similar character again, I'd probably take the suggestion one poster made at the bottom of page 1 of starting 18/14/16 post-racial and then pumping Str/Dex straight up.  Having the Dex for HBO at paragon doesn't hurt, either--Pressing Strike makes an incredible OA that can frequently disrupt whatever the enemy was trying to do, since even if you miss you get a shift 2 that can easily drop you into the space they wanted to move through.

Darkwing, I'm having trouble seeing how HP can compensate for low defenses past early paragon.  In my experience, whenever he really started doing his thing, especially setting up an encounter nova, my barbarian would immediately draw fire from pretty much every enemy on the map, since he was set up to kill several of them at once.  I've never played a Rageblood, but I did get frequent Resistive Formulas from our Artificer, and even with some effort put into AC, it was unbelievably easy to take more damage than a big pile of HP could reasonable absorb in about two rounds... although tbf, my DM started attacking my Reflex regularly by paragon, so AC investment had somewhat diminishing returns.

Unless we're talking lower level than I'm imagining, I would expect a Barbarian doing good DPR and getting hit a high percentage of the time (or pretty much all the time, which is where relying on hide with no dex scaling will get you before too long) to take way more than 20 damage per round, to say nothing of inconvenient status effects he'll incur (again, fewer of those to AC, but the ones that do, like daze, immobilize, and ongoing damage, can be a pain).  In practice, how many attacks are you talking about taking per round, for how many hits and much damage?  I'm curious how any reasonably damaging melee striker with near-autohit AC manages to stay up, and I assume I'm either missing out on some math, or your combat experience is very different from mine.