I think both play the role very well...but I do like Quinto slightly better. Further, Quinto was the one Nimoy himself approved of how he played the part and felt he was entrusting it into good hands with him (not that I think Nimoy probably wouldn't have thought similarly of Peck had he gotten the chance, but still).

I’d say Peck is better, but he does have the advantage of playing Prime Spock instead of a weird alternate timeline Spock.

What's weird about alternate timeline Spock? Other than, you know, that he's from an alternate timeline and all that.

After all, Peck's Spock is the one who's going around creeping people out with his unnatural smile and all. :-P

Its just that he is technically a different character with a different history and a destroyed planet and a romance with Uhura for some reason. He is not the Spock we know and he never will be.

Peck’s Spock has his odd relationship with Chapel, and he was experimenting with emotion, but we know that he is on the path to becoming the Spock that we all know and love.

I suppose that's one way of looking at it, but then I also don't see why that needs to be treated as if it's a bad thing.

Its not a bad thing. Its just that I don’t quite see Quinto as Spock Spock. He’s fine in the role, but he’s still not quite Spock.

I like both. But I picked Quinto because I called it before he was cast. I remember watching Season 1 of Heroes and thinking "Sylar would make a good Spock." And sure enough, it became true.