I got to go with Xenia Seeberg for the more attractive Xev, particularly in the later seasons when she had her hair a little longer and not as bright. But that's just me.
I think Stanley for the most part was my favorite character. I've seen plenty of show that star "the everyday ordinary guy" but Stanley really is one of the few that really felt like an average person. He could be weak willed, selfish, was a little older and not quite as attractive as he would have been if the show had been produced now a days where even the nerds of a show look like fashion models.
I think the fact that Stanley is the everyday ordinary guy in an odd situation with really out there people. It just adds to Stan. It just somehow does.
Also when you consider that the robot head 790 is never going to die and it forced to exist with his brain completely distorted by that love slave transformation, originally meant for Zev. Forced to be obsessed with someone with no body off his own to do anything about it in that sense. You gotta wonder who has the worse fate? Also Ironically 790 programed the curse he is enslaved by. But Zev got away. Cruel twist off fate ey? Kinda Karma in a way...