I would marry one of the three. I love the british menof BTVS/ATS so here they are.
Wesley, duh, needs someone who can understand him and help others understand him. Sometimes I thought he needed a translator. But he also needs to be loved, he didn't get it that much, and I don't think his relationships with Virgina and Lilah where good for him.
Giles, alway alone, the solid as a rock watcher. Also has the former bad boy thing going, his wild days when he did black magic with Ethan. And who could forget the singing and guitar, made me all warm inside. Didn't have much of a life, was always known was a watcher and that pretty much all he did. He needs the love just as much as Wesley.
berkeled may kill me for this but the last is Spike. Yeah who could not love that vampire. We probably have the same taste in music along with everthing else.
And to have those eyes look at you, you'd feel like he was looking into your soul and you'd feel like you melted into a puddle of goo at his boot clad feet.