First of all, I want to say that it was right that Buffy didn't end up with either vampire. She had her own life to live and revolving it around Spike or Angel wouldn't have helped.
Aside from that I have always been a Spuffy fan. Frankly, Buffy and Spike made a dynamic pair. It was interesting to watch two people, who first met as enemies, learn to give up their pre-conceived ideas of each other, endure so many complex problems and mature as sentient beings, together. Yes, Buffy/Spike was not as "romantic" as Buffy/Angel, but I never cared for idealized love or Gothic Romance - which Buffy/Angel clearly seemed to me. I find Idealized Love to be boring, cliched and immature. I also think that Buffy and Angel would have never made it as a couple . . . and not just because of the curse. One, Angel is a control freak who would have continued trying to inflict his will upon Buffy. And while Buffy would have tolerated it as a young girl, she would have never tolerated it as an adult. Also, Buffy is a bit of a control freak herself. But most importantly, whereas Buffy (and even Spike) had managed to develop or mature as characters, Angel never did. Their conversation in "Chosen" made it pretty clear to me.