Someone gorgeous with a lot of power... an example would be like Jaina the Lich Queen. Reasoning? She could bless me with immortality and awesome power, and she's pretty damn sexy.
I'd certainly enjoy having a romantic relationship with Lirael the Abhorsen. <3 I just fell in love with this character, and she also happens to be pretty damn powerful and attractive. Also, her house is on the edge of a waterfall.
Elizabeth Comstock earns and honorable mention here. I never played the game, but hell... there's an infinite number of her, and they can take you to other worlds and realities! That's like, one of the best powers out there.
My other option would be a female version of the Doctor from Doctor Who.