Personally, I have no preference as I've never seen any tile wear out. My projects generally call for porcelain because it's more expensive.
No tile holds up to impact damage. I think porcelain would probably hold up a bit better overall.My biggest concern is the ability of the tile to survive something being dropped on it. Lately my kid dropped ~3lb pyrex dish on our current wood floor. There is a big mark on it.
Now, how would have either tile kind reacted to this?