I think it depends on how you look at it. Sure, you could argue Sunshine had more depth, but had some terrible character and stage designs and omitted some key aspects of a Mario game. Fludd was fun at times, but I would rather just have regular power-ups. The enemies and bosses were uninspired (the final boss in particular was a huge letdown) and so were the stages. Mario 64 stands out in particular because it got 3D right on the first try...something Sonic STILL hasn't done after several games. Also, I think it should be noted:
Galaxy>Sunshine