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.
ITA. I remember the first time I saw John De Lancie, it was not in Star Trek, I think it was in his small (and quite pervy
) role in a movie called The Hand That Rocks The Cradle. I thought "this man has such an interesting face... not conventionally handsome, but there is something very intriguing about him".
But, fun as Q is, I always found him petty, childish and annoying, and that pretty much erased the possibility of any sex appeal. (Sorry, Q lovers.)