Island Defino, great stage good for Wolf with Left/Right B move sweet spot.
Final Destination, awesome for Mr.Game and Watch's awesome jump moves. And the flat plain works great for Snake.
My faves are Final Destination and Halberd, though I also like 75m and Luigi's Mansion.
If we can include Custom Stages, then I'll have to say a custom stage I made, F. DESTINATION??? is a fave - it tries to imitate Final Destination, though it's larger by about 75% and has two thin platforms neatly tucked away at the bottom of the stage.