Eldiran
Smash Lord
I'd have to say Metaknights' Up+B. It's simultaneaously a potent kill move, incredibly effective recovery (excellent vertical height, and a glide afterwards), and a nigh-impregnable defense against spikes (it attacks of most all of the move, and instantly moves him a great distance). Not only that, but if you miss with it, you can get another chance at a (strong) attack!