I like Xenogears when it comes to looks. Although I personally though Fenrir was pretty badass. I can't help but like Vierge, but that is probably because Elly was my favorite character. Andvari was cool looking, but that was about it. Same with the Omnigear version of Stier.

Also, I like Seibzen because, well, Seibzen is a cool sounding word.