I didn't enjoy IM2. I may be rare in that regard but, while I can't really point to any one thing about it, I felt it lost the flavor of the first film. Micky Roarke was excellent as the bad guy but I was less involved in that film that the first one, which I saw three times in the theatre. It's worth seeing but it just doesn't live up to the first one.
I really liked Thor film and Captain America. Like you, I prefer the Liv Tyler and Edward Norton HULK.
I have seen The Avengers twice now, both times in 3D and I'm considering seeing it a third time in 2D partly for the contrast and partly because I just adore that film!