As for who looks strong coming out of testing, it will be close between Ferrari, McLaren, Mercedes, & RedBull. Lotus/Renault & Sauber will be close too.
Ferrari will be improved in Alonso's hands and should be able to compete for wins out of the box this year.
I think the field will tighten this year and the mid-pack teams like Force India and Sauber will get in the competitive mix more often.