>>35984576Colosseum. It was just more enjoyable. XD felt like everything was phoned in. I don't remember enough about the mechanics themselves to split hairs over the two, but the environments, the characters, the story itself, even the music, all are points in favor of Colosseum. Plus, it has the sheer novelty factor, being the originator of most of the concepts of the two, being a wild break from the mainline series both in terms of gameplay AND the tone, with an edgy criminal protagonist on a motorcycle with two non-starter non-shitmons you get to battle with right off the bat at level 25 instead of pick your color grind and go. It was just fresh.
In a vacuum, maybe XD would have an edge, but we don't live in a vacuum, so I can't answer without my own experiences coloring my opinion.