For me, it will always be Bastila Shan from KoTOR.
Even for those graphics, she's quite attractive, and unlike other Star Wars love interests, developing a romance with her didn't feel forced (though I guess it was Forced, given the bond... oh, nevermind).
She also had interesting character development and seemed like a real person. She got arrogant as a somewhat-experienced Padawan who suddenly had a position of authority (I know I've made that kind of mistake a couple times in my life) and she began to question the teachings she preached as she compared herself morally to my character (whether I was light or dark).
So yeah. If you say "Star Wars romance," I will think of Bastila long before I think of Leia, Padme, or Juno.