i'm not sure. but at this point, i might rank it #1.
i guess the key to determine where it ranks depends a bit on how it lasts the test of time.
i used to think Spider-Man 2 and X-Men 2 were great. but after having seen them more over time, i've gotten to a point where i don't really enjoy them that much anymore.
even with Batman Begins. it's not tha great to me anymore. i even liked X-Men 3, Spider-Man 3, and Fantastic 4 2. but now i find it hard to even get excited watching these flicks.
and ofcourse, the 2003 Hulk hasn't held up from my initial thoughts about it.
Iron Man and TIH are the most current superhero movies that i have enjoyed, but i actually enjoyed and felt more excitement from watching TIH over Iron Man. and for some reason i can see myself enjoy watching TIH more often over time, than Iron Man.
and for the longest time the superhero movie that i really considered #1 was Superman 2. but by this point, the special effects don't hold up too well now. so, now i'm torn about it.
but for now, yeah, i think The Incredible Hulk is the best superhero movie made. i thought it was very exciting. i loved the action scenes. the cgi was great. and the acting was very good. the humorous touches were great. and the way the plot tied in the Super Soldier Serum was awesome.