Spock! Always and forever, Spock.
Kirk's face is prettier, but Spock's face is more interesting, and I'll take interesting over pretty any day. Once you've seen Kirk's face, you've seen it, but I could look at Spock's face all day long. I also like his slender, less-bulky physique; we don't all want body builder types.
He even has beautiful hands. Oh, and that GORGEOUS voice!
Of course, it's quite possible that I like Spock's looks so much because I like HIM so much -- the wonderful mind, the unstoppable curiosity, the devotion to science, the excellent ethics, the loyalty and devotion that he shows to his shipmates in general and Kirk in particular, and on and on and on.
I first saw Spock in 1969, when I was eleven, and he was my first-ever crush. I'm 55 now, and I STILL have a crush on Spock.
It amuses me to note that I married a man who's a highly intelligent scientist. My husband is tall and slender, with dark hair and a long, thin face. But no, I didn't marry Mr. Spock, because my husband readily expresses emotions. He also doesn't have a bowl cut.
If only my husband were capable of mind melds ... I'd really like to experience one of those.