Prozac is supposed to be the most stimulating of the SSRIs, so that would likely meet your demand for lack of sedation. Paxil is generally deemed the most sedating SSRI (though I personally can't tell any difference between the two -- individual results will vary greatly).
As for sex drive, Zoloft killed my sex drive. Which is totally different from Paxil & Prozac that didn't harm sex drive, but made it impossible to orgasm. Now there is a cruel irony: one drug (Zoloft) that lets me orgasm even though it takes away any desire to do so, and two drugs that still leave me horny, yet totally unable to orgasm even if my life depended on it. As you might guess, I'm not a fan of SSRIs, though they do work for some and you might be one of those lucky ones.
As for weight gain, I personally don't think SSRIs have much effect on weight (though if they do it's certainly in the upward direction). The weight effect of SSRIs isn't so strong as to be obvious -- it's not like Zyprexa that virtually comes with a guarantee of obesity.