Spock is a humanoid. Data might have his “fully functional” parts and programming, modeled on humans’, as everything else about him is more or less modeled on humans. But Odo, while he might be able to whip up some anatomical semblance to the necessary organs, is a completely different sort of life-form and has nothing analogous to a humanoid sex drive.
Your assertion about Odo is contradicted b the series itself. Odo pined for Kids for years, had a sex life with her that both seemed to enjoy, clearly had good sex with another woman, and in her another occasion was seen appreciating the rondeurs of a certain Bajoran blonde.
I SAID I made a mistake, woman. What do you want, blood.
Fine I will send you however many quarts of hobbit blood it takes to bleed a hobbit to death. Somebody check.
Must have missed those eps; I was thinking of the one where Lwaxana Troi had a thing for him.
Mom thought Nimoy was hot.
My little sister did too.
Spock was deliberately designed to look a little bit Satanic, what with those eyebrows and ears. The female fans just can’t resist Satanic.
No, that isn’t my own observation. I read it somewhere a long time ago – pretty sure it was right there in The Making of Star Trek by Whitfield.
Spock for sure. Data not so much.
So Odo. Well. Um. Am I the only one who thinks it would be cool to have one partner with as many, er, appendages, as I want? Hot, no. But if he was someone I was around a lot and got to thinking about it, and then we went for some drinks and I thought about it some more. Yeah, I’m pretty sure my drunk ass would be taking him home.
No blood required. Ick.
Especially not Hobbit. Orc maybe. 
Model Paulina Porizkova says her initial attraction to Ric Ocasek (lead singer for The Cars) was his resemblance to Spock/Nimoy, on whom she had a huge crush in her youth.
Mother Tricor: a woman of excellent taste and refinement. Nimoy was hot at all ages, Spock was hot at all ages.
Data was adorable, but never hot. I plead lack of knowledge on Odo, but photos would indicate not hot, perhaps lovable.
Unasked but also true: Worf was hot.
No love anywhere for Neelix?
I never found Spock or Data or Odo sexy
I think females find Spock sexy because he acts like he has no emotions but keeps them hidden underneath. They think they can change him and bring out his sensitive side
Odo: No
Data: To some real weirdo maybe, but mostly no
Spock: For people attracted to a certain type, yes.
Spock: Absolutely, at all ages.
Data: Could be, with minor adjustments.
Odo: Not when he was being, say, a chair.
I have no particular opinion on whether Spock was sexy.
I am fairly certain, however, that he was neither Data nor Odo.
I’m a tad skeptical of the accuracy of your recollections, and the whole “Odo has loved Kira for years” thing struck me as a tacked-on romantic subplot in the later seasons because somebody thought the show needed a tacked-on romantic subplot.
No. No. No.