You could show a game wall of text for each one to prove one is better, but obviously Mario is better on Wii, I personally enjoyed TP over WW (and, bonus, we got SS!)
Sorry, if I point out the obvious, but, Twilight Princess was originally
only for the Gamecube, although it was a good game to start out with on the Wii.
As for the Mario comment, my opinion is that Sunshine is better, but I am rather biased towards the Gamecube as a generation seeing as though I grew up with those games.
But, Sonic is better (in my opinion) on Gamecube, because Sonic Adventure DX Director's cut was much better (and has better controls (and no werehog)) than Unleashed, Colors, Black Knight, or Secret Rings. Also, It had Chao. Enough said.
I think that the Gamecube and the Wii each have their high points, But to me, the Gamecube was better. Everyone has their own opinion, we should stop arguing over menial things such as this and just play.