I'll be honest with you, I'm not a fan of the convention that when superheroes meet for the first time, they must fight. This is especially true of inter-company crossovers. It's boring, it's annoying, it's frequently out of character and it has a host of other problems.
However, there is Michael Habjan's "Superman Vs. Hulk". There is no plot. There is very little characterization. There IS, however, some extremely watchable homebrew CGI. What makes this fascinating, is that you can see the progression in Mr. Habjan's skills as he posts new segments.
This guy is getting pretty good at this, isn't he?