I've always like Ireland but I think they're still recovering from the loss of O'Gara. It's been years since he was on top and they have Sexton, but O'Gara would take those close games and win them for Ireland. The backline and forward pack could both work off of his plays. Of his 15-ish drop goals, 10 were at the end to win the game.
I still think they could win it, but it'll be a hard one. They have (arguably) the best backrow, the second best front row, second-best locks, best 10, best centres (when D'Arcy and O'Driscoll are there) and a good back 3. I'd favour Wales or England ahead of them, but I would be disappointed with less than 3rd.