Metagross has better HP, Attack, Defense, Speed, Special Attack, and learns better moves. Spiritomb however has absolutely no weaknesses and slightly better Special Defense. I like steel-types more so I am definitely going with Metagross.
Lol, JesiahTEG is one of the most feared battlers period(he just beat a smogon admin who had a poke that would tear apart his whole team). He says it's better to go with offensive pressure than to stall with defensive chip damage teams. Metagross offensive, Spiritomb defensive. Metagross wins, and that on top of that he's way cooler anyways.