The taste in this thread is top-notch. Just sayin'. Sena in particular is a beauty. She's got a great body and pretty face, she's smart, likes video games and forms emotional bonds with fictional girls from said games. She'd be on top of my "list of top waifus of all time" if she were a little more easygoing. She's a bit too abrasive and confrontational for my tastes, but other than that she's pretty great.
For myself, do you really even need to ask? My waifu has been my avatar for... a few months, at least. Granted, a good half of the Neptunia cast is grade-A waifu material, but Neptune takes the cake. She's laid-back and easygoing, yet energetic and optimistic, plus she's adorable and creative and way stronger and smarter than she lets on. She's friendly, eccentric in her speech patterns, and loves video games. She is a bit lazy, but when you're a physical goddess, you can afford to be. Speaking of being a physical goddess, if she seems flat-chested in my avatar, well, that's 'cuz she is, but her alternate form, known as Purple Heart, has an absolutely killer figure. I can't provide any pics right now, due to me being at school and thus not having the luxury to go image-hunting, but if I remember to I'll edit some in in a couple hours. My commute's a *****. >_<