Okay we all watched Tom and Jerry chase each other around and beat each other senseless. Did you get more excited about Tom with just Jerry's tail hanging out of his mouth, or laugh harder when Jerry managed to clobber Tom. I have to say I prefer the underdog or in this case under mouse, or might mouse... oh wait, that would be another cartoon altogether.
I wish Tom would win sometimes because he gets badly beaten every time but I hope he wouldn't eat Jerry since that will be the end of the story.
It depended on the situation. If Tom was being really mean, I'd root for Jerry. And if Jerry was being really mean, I'd root for Tom.