I've always had a thing for fair-haired gentlemen with high cheekbones, so naturally Raphael was the first character I took notice of when I picked up SC2 for the first time. I do wish the goatee from his 2P costume would make a comeback. He's got a lot going for him, in my opinion: dancer's grace & athleticism, sword skills, intelligence and interpersonal savvy (if not tact), and the ability to commit to something (even if it's a little excessive by now, but over-used story elements ail most of the characters, not just Raph). And I have no problem with an opponent breaking my costume during play, because then I get to stare at DOSE ABS after winning.
Siegfried is another favorite, though I really hate to see a man with long hair. His short-haired 2P costume in SC3, though, plus Crispin Freeman's voice, damn. I do dig the stubble he's rocking in 5. He's gotten stale with his lone knight concept for the last three games, but the notion of a man who wants to fix his mistakes is appealing.
While I'd like him to be a more traditional werewolf (I just like werewolves, they're simply cool to me), Zwei always makes me drool over his human self. White/gray hair, muscular build, tattooed...I'll take two; no, I don't need a bag; thanks. Too bad he doesn't have much in the way of character. Maybe next game.
Not fond of his costumes generally, but Zasalamel's one handsome man. Not many people can pull off an eye tattoo, but when you've had several lifetimes to get it right, I guess you do. Let's not forget that the man uses a scythe as a weapon. If that isn't cool, I don't know what is.
Kilik's a nice guy. I like nice guys. Easy on the eyes too.
Yun-seong's likable for me as he's energetic, athletic, and well-intentioned. I hate his hair style (it's like someone mixed Viagra with Rogaine), but the bandana he wears in his 1P SC4 outfit fixes that.
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While looking at ladies isn't my style, I would love to play the role of wingman (wingwoman?) while out manhunting with Ivy and/or Viola. That would be a night to remember.