I disagree with both of those. Spider-man 2 was definitely the best in the Raimi series, but I don't think it's the best Marvel film. I'm not a fan of that series in general, I would have loved Spider-man 2 if they portrayed the characters of Peter and MJ differently, not a fan of Toby McGuire and Kirsten Dunst.
As for X-men 2, I hate that entire series. Actually, I can't say that for sure as I have yet to see First Class, while it looks better than the others, I don't see myself loving it.
My favorites have to be Iron Man and The Incredible Hulk, both movies are just great. Iron Man especially really did a good job, RDJ really is perfect as modern day's Iron Man. To me Iron Man is a perfect example of a comic book movie done right.
TIH is good too, I really love Ed Norton, the opening credits and the cinematography in general. It's one of those films that I love to look at and I'm not quite sure why. I can understand why some people might feel different about it though, it does drag in some parts.