Sorry for not voting, I just can't answer in a black or whiter manner. So here's my opinion.
My general preference, as a guy, is a girl who is generally fit/average. I've seen tons of girls who others might consider chubby, but they are taking care of themselves and it doesn't give out a negative image. Curves are the way to go. Of course, when it comes to dating, if a girl is really skinny but is awesome, I won't think twice.
As MaskofInsanity expertly said, confidence DOES draw us to a girl. Might I add, a bit of playfulness helps too!
I like women with a little meat on their bones. My exwife was heavy. I have a few pounds myself. I don't consider myself fat but a really skinny person probably would. While I wouldn't turn away a skinny person I would not go after someone who was too tiny. I am 6'3" about 275. I don't want to feel like I will hurt her if I am laying on top of her.