I like em both, and the only game they're both in, is Kingdom Hearts, and they're on the same side (well at least in KH2 that's clear)

As for the whole Zero thing, zero is just cool, because he has a sword. And I own every Megaman Zero game, and they're fun and hard at the same time, but I definitely enjoy using the sword. Plus they're better for Zero than the X games because it was designed for the sword, while the X games were not, they were designed for X. So, when I play X games, I use X, even though I do think Zero is cool cause of the sword, and then I enjoy the Zero games.

But back to the topic. Who's better? Well, at what point? It's such a biased opinion, if you like one character better, you can't even analyze the situation. There are so many things to determine, what world is it in. Do GFs exist, does Materia Exist. What weapons do they have. What level are they. Why would they even fight to see who is better.
(note, all those questions should have one of these ?)

Anyways, what I'm saying, is it's a pointless argument. Do you like red apples of green apples better? You can't tell which one is truly better. They're both apples, so it's just about your preference, you can't honestly compare them and say one is definitely better than the other.

THE JACKEL