When concerning just looks, Kirk is the most attractive to me, with Kevin Riley at second.
Kirk is terrible relationship material though.
I can see the appeal of Spock. Look at the relationship with his parents to see how Sarek clearly has a close bond with Amanda. I'd think that would be the kind of relationship Spock could have. He does have that vibe that makes it seem like you'd be the only person he'd express himself to.
Now for me, McCoy is the best husband material. He seems like he'd make a fantastic husband.