Does Luigi's Mansion for gamecube count? :D
I ADORE that game, it's my all time fave for mario games :'3

If that doesn't count, then I would have to say Supermario Sunshine for gamecube!
It was really fun running around and looking at a 3d mario world way back when :'3

For the gameboy era, I do not own this, but playing my friend's copy of Super mario world 3 was Incredible...I love the haunted mansion parts :)