Number 1 for me would definitely be Nico Robin from One Piece. If one were to ask me to be as chauvinistic as possible, and make my own dream woman, Nico Robin is the closest thing to "the perfect woman" to me.
She's cool, collected, articulate, always knows the right thing to say in practically any given situation. She has a macabre sense of humor that I really like. Her desire to always learn more and better herself is a real turn-on for me, and if you earn her trust, she is faithful to the very end. Seeing her try to live and survive after her backstory is enough to make nearly anyone just want to hug her. Plus, it doesn't hurt that, despite Eiichiro Oda's proportions, she's physically what I find the most attractive. Black hair, blue eyes, tall(which means killer legs, and I'm a legs man), with slightly tanned skin. Hey, I said I was being chauvinistic.
Number 2 would be Liara T'Soni from Mass Effect. I think she is the best developed love interest character from the series, because you have a strong arc that spans across all three games.
I find the way she says nearly everything so innocently in the first game to be adorable, and I couldn't help but be entranced by her big, pretty blue eyes. Watching her progress across the games as she becomes more hardcore by the time the second game kicks in (and reading the comic tie-in, Mass Effect: Redemption), and beating LotSB, and hearing what she has to say afterwards is just great writing for a couple who've had to deal with a two-year disappearance. Her dialog to you, if you beat LotSB before the suicide mission, is much more than "Let's copulate before rushing into certain death", its fear of losing a loved one for a second time. It feels far deeper than any other romantic option, and more interesting to me.
Those are the two I just really like. Others I like are:
Catwoman (Selina Kyle). When she's got a good writer behind her, she's one of my favorite Batman characters.
Jasmine from Disney's Aladdin.
Inara from Firefly.
Major Mokoto Kusanagi from Ghost in the Shell.
EDIT: Marion Ravenwood from Indiana Jones.
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