I only have the Gamecube version, but I've seen the PS2 one...
interesting no one brought up difficulty. I believe there's an easier mode on the PS2 version.
The Gamecube game is hard. There are two settings "Kids mode" and "Adult mode". And unless I'm mistaken the PS2 version has a third. My stance is that you'd be robbing yourself of time spent being really challenged by the game if you buy the PS2 version just for the extra difficulty mode. But there again -- if it's too hard, you may not like it at all. So if I'm right, thats one thing to consider.
I don't know why but I seem to remember thinking the PS2 version looked ever so subtly duller, and something about the way it moved wasn't as good as the Gamecube version... but make no mistake, it's still a beautiful game on PS2.
Finally - Dante... just doesn't matter.
I would personally advise you to go for the Gamecube version. But if you forsee having difficulty that you wouldn't like shell out for the PS2 version.