Hearthpwn

Warlock by far.

I think people underestimate Warrior though. I agree it feels very weak comparing it to other hero powers in a vacuum, but it synergizes really well with the hero. Warrior has Shield Slams and weapons, which work well with armor. It's a very powerful class and one of the main complaints about Warrior being so strong is that they accumulate so much armor, making some match-ups like Freeze Mage, really good.

Hearthstone works as a rock, paper, scissors game. TGT brings new cards, new mechanics and new synergies. Yes, the aggro decks wills improve. But so will the control decks, not to mention completely new decks that will influence the meta.

As we've seen from Blackrock Mountain (Emperor Thaurissan and Grim Patron) new decks can rise with the addition of one or two cards. Grim Patron and Malylock, two of the best decks out there today, did not exists before Blackrock Mountain.

If aggro decks infest the meta, the meta will balance itself. That's the beauty of Hearthstone (and the comparison to rock, paper, scissors). If a lot of people are picking rock, eventually people start picking paper, and rock will no longer be a good choice of weapon. There's enough powerful healing and removal in the game. Whether you should play it depends on the metagame.