Physically, I'll take anything that isn't F A T fat. Some self described BBWs meet my criteria, most don't. If you won't take care of yourself, that's a mental and physical turn-off. The rest are just preferences.
Hair: Red is my favorite, but depending on the girl wild colors like blue or neon anything will do the job. Blondes tend to rank last.
Height: Tall preferred, 5'10" (178 cm) and up, but 5'2" (158 cm) to 4'10" (147 cm) really works, as long as they're tough chicks.
Body: Not fat, not so skinny I'm afraid of breaking her.
Race: Generally fond of medium dark skinned ethnic minorities. Asians, Latinos, Indians, etc... Espicially Thai and Phillapina.
Other: Freckles, ability to kick my ass up and down the street without breaking a sweat, super long hair.
All of that is secondary to what I like in a woman's mind. Smart, sarcastic, and independent are absolutely required. I like crazy, as long as she's still capable of taking care of herself. Atheist/agnostic preferred, but open to most religions as long as they aren't militant about it (absolutely no Scientologists). Preferred interest in math, science, or artistic fields.
In short, I was once insulted (deservedly) with a quantum mechanics reference, and proposed on the spot.