Leeta! I have a thing for redheads and she has the sexiest smile.
When I was in high school, I loved Ezri's neurotic nerdiness. But as I get older, I find myself more often craving the more direct womanly wiles of Jadzia. "Let He Who Is Without Sin..." is a crap episode but Jadzia makes it worth watching if you turn the sound off.
Kira Nerys has her moments but I'd much prefer her Mirror Universe counterpart. She may kill me afterwards but I think it might be worth it.
And for an unconventional choice, I'd also add Natima Lang, Quark's Cardassian ex-girlfriend.