Man, this is tough.
Let's go by series though:
TOS - Nurse Chapel IS hot IMO, despite her total dearth of votes. I love the TOS uniforms... relics from back in the day when men openly saw women as sex objects instead of now, when they just pretend not to. Uhura was ruined for me by the movies.
TNG - Troi... blech. Robin Leffler... cute, but irritating. Ro... never smiled. That's a huge turnoff. Hmm. Nobody else even merits a mention from that series.
DS9 - Now here's a series with attractive women. Jadzia totally wins, especially given the episode on Risa. Ezri was incredibly cute, but cute is a far different thing than sexy. Kira was hot in later seasons, but her hair in the early ones was really, really bad. My fav though has to be Leeta, the dabbo girl. Amazingly attractive, that one.
Voyager - Another good show for attractive females. B'elanna looks like Alyssa Milano with head ridges, which is always a good thing. Kes was cute, albeit an irritating character. Too sacharine. Then there's Seven. Ahhh... Seven. Seven was lovely. Too bad they got rid of her old silver skin/outfit thing.
Enterprise - T'Pol is the obvious choice here, if it weren't for the recent Risa episode. Hoshi looked freakin' great in that episode! That put her to the top of the Enterprise hot list for me. Plus, T'Pol has a weird lip thing happening.
Overall though, I'd have to say that the image of Jadzia in a swimsuit sticks with me most of all.
If only all Trek shows had manditory 'attractive women in bathing suits' episodes.
edit: I just remembered the DS9 episode "trials and tribbleations." Jadzia in an original TOS uniform. She definitely wins now.
-F