Tought choice, very tought choice. I really liked Blade I, Dorf was at his best and Snipes wasn't too, well, Snipes.
Spiderman I thought really took the next step in the Comic to Movie Genre, no thanks to the brilliant special effects and a great cast (J.K. Simmons as J. Jonah Jameson was a crack up).
X-men and X-men 2, apart from Halle as Storm, were pretty much perfect. I have no idea who is doing the casting for these movies, but keep it up. Ian McKellen and Hugh Jackman pretty much steal every scene they are in.
In the end I went with X-men I, as it avoided the pitfall every other Comic2Movie has made; It didn't kill off the villains. Why did they do this in Batman, Spiderman, Hulk, etc. It just doesn't make any sense what so ever. That is why X-men I gets my vote.