TOS Spock, natch, and Mark Lenard as pretty much anything, but after that, I picked Picard, Chakotay and ST09 Spock. I meant to pick ST09 Pike...but I forgot. Oh, well. Somehow I think he'll do pretty well even without my vote.
I adore Q, and I think John DeLancie definitely has sex appeal as a actor, but the character Q...too puckish and too inclined to consider mortals along the lines of reasonably bright cockroaches, so not so much.