Bit of both I think.
More often that not, very shy guys tend to be wimpy and don't have the nerve to do anything about their feelings, whereas outgoing/confident guys do .... (personally though, not too keen on the LOUD/cocky qualities)
I definately go for the shy and quiet ones. They're much more kind and sensitive.
Plus the cocky ones are all full of complete Bull****
and normally i spend my time trying to outsmart them if I come across one.
i go for the manly man. my man has a look that says don't fu*k with me, yet he's the life of every party. he's a great dancer,funny, very sexy. but yet he don't take no crap. that was a big turn on for me! he's not the kind of that needs a pick-up line. the more he doesn't notice you , the more you want him. i love the "i don't give a f*ck"" attitude. yet he can be so sweet and thoughtfull.