Magistrum said a good portion of what I was going to say. I'll just add that I like Sableye's design more than Spiritomb's - I mean, Spiritomb is more obviously sinister, which is a point in its favor, but Sableye hits a nice balance between cute and creepy. Those huge crystalline eyes, the manic grin, and the hanging claws just look so excellent. (The fact that Sableye eats gems is also pretty cool.) To top it off, Prankster Sableye is one of the most effective trollmons in competitive play, and I love annoying my opponents.
Yeah, Sableye all the way.