Mario Sunshine all day. I laugh at these fools saying that Galaxy looked better, has anyone seen the water effects in Sunshine? They look amazing, especially for a 2002 video game, they STILL look good today.
The game had a nice concept too - Mario goes on a vacation for once and it goes down, interesting, and the FLUDD was very awesome - It allows you to defeat enemies in a different way and helps you reach far areas and once you're used to it they take it away to up the challenge in some missions. And it had a better plot - common, how many really saw who Shadow Mario was? The areas were very intriguing and it had a more free, sandbox feel to it. And the game had Yoshi, it didn't take another full game to put him in.
People complain that the voice acting was bad but common, what else did you expect from a Mario game?
In other words, the best Mario game so far, better than Galaxy and one of the best on the GameCube