I'm a huge Marvel fan. Captain America has been my favorite of the bunch. Loved me some Hulk (the one with Edward Norton) and enjoyed the Iron Mans. The only Marvel movie I didn't enjoy was Thor.
That being said, I am EXCITED for Avengers. Going to be waiting in the midnight showing line while reading some Ultimates (Ultimate being my favorite universe). It should be a great film for both comic book fans and those that don't read comics.