Like Snare said, Liquid is the favorite to take the American qualifiers, followed by either NAR or SNA, and the inconsistent Revenge (Personally, I think SNA has an equal shot if not a better one than NAR).
Also, I'd like to point out, the team that wins these qualifier will need to put in some immense work in order to match up to the invited teams (perhaps boot-camps are in order). I say this because at this point I've seen all the teams in the qualifiers play more than one match, and I must say there is a lot talent on the teams, but team decision making and the amount of tactical errors being made is alarming.
Anyway, Team eHug really surprised me (their team-play in certain games especially); taking a game from both SNA, and Revenge the day prior to that. They may just pull of more upsets, but then, consistency is a concern.