My personal ranking right now on NA its Gravity/Team liquid/TSM
Gravity is so polyvalent, they are finally accurate on shotcalling and strategy, they have the best of a best-of-5 if they can hold on mental thoughness.
My last doubt on Gravity is the biggest reason why Team Liquid is ranked second. This team is so tough, whatever happen IWDominate has a plan to bring is team back during a game, and everyone still beleive. It's a very very solid team.
TSM are better on paper of these 2 up there, but if there first strategy fail, they lose, they can't adjust in game at all if it doesn't go their way.
If they are behind they can rely on a good teamfight and that's all. I really don't think they are serious contender.