Sketch - Superman VS Hulk

Two of my favorite super hero since child hood, if I am not mistaken, they are the strongest from Marvel and DC. Wonder there are any comics crossover for this two characters, i am pretty sure there is no movie nor cartoon story for them.

Any idea who is stronger? I personally will vote for mmm......think not easy to choose.
Just browse through the web and found the below link, perhaps the website give us some answer.

http://www.mania.com/superman-vs-hulk-would-win-fight_article_117660.html

My sketch is amature level, but i like drawing, especially gilrs, I will post some girls sketch later. Stay tune.