As a video gamer, Mass Effect from Bioware has introduced a lot of new and sexy aliens to my sci-fi landscape.  At the top of the list are the asari, an all-female race of blue-skinned babes that mate with other species (almost ANY other species).  They're also long-lived, with younger asari leading near-hedonistic lifestyles as they explore and experiment around the universe before settling down to raise kids.  There's even a genetic anomaly among asari that create Ardat-yakshi, a kind of sex-vampire that gets off on devouring their partner's life energy.

They also have small tentacle-like protrusions for hair, so it's basically every alien-sex fantasy rolled into one species.

I'd apply my usual high standards - breathing, has a pulse, bad eyesight.. and go form there

Another Trekkie here :-) But how about Klingons? My fave quote about Klingon romance is...

“Men do not roar. Women roar. They they hurl heavy objects. And claw at you.”
-- “What does the man do?”
“He reads love poetry. He ducks a lot.”
(Worf and Wesley ST:TNG)

If I had to chose I think I would still chose human mates, no alien has awaken my interest so far. I don't recall seeing a naked alien before, that's a factor too, isn't it? wow nude

Several years ago, when Farscape was still active, the Sci-Fi channel did a survey of the hottest sci-fi babes. All of the females from Farscape were on the list with Chiana being ranked highest.

Call me prudish but I'd have trouble enjoying myself with anyone that I'd have to worry about stealing my stuff while I slept. I have no doubt that the sex would rock but I like the before and after too.

Therefore my top vote has to go to Amanda Tapping of Stargate SG-1. She's smart, blonde, sexy, trustworthy and can be very caring. She also never seems to get any so I have no doubt that her pent-up frustrations would be something to experience once released!

Zhaan is pretty sexy.

Hmn, I don't know off the top of my head, though Chiana does spring to mind.

Definitely a Star Wars fan over Star Trek here. I'd go with a Twi'lek.

anal probe.

He's half-alien, anyway, right? He's probably got it all down to a science.

Hahahahaha, fantastic! I have to ask, have you ever read Larry Niven's "Shall We Indulge in Rishathra?"  (I think that's the name of it; it's been awhile since I read it.)  It's a short story/article in "N-Space," about the difficulties presented by inter-species alien love, comprising a list of possible responses (including, as I remember, "Sorry, you have too many/not enouch orifices.").

My answer to your question?  ...Hmm...  I'd have to go with Chewbacca.  Probably not the most skillful, but you get the feeling he'd be grateful for it.  :-)  lolololol