It really depends. I'd probably have to go with B, though, because a snappy dresser is usually very confident and likes himself. I don't mean a narcissist (which sometimes is the case), but a guy who's less critical of himself tends to be more fun to hang out with.
guy B. knowing how to dress well is important to me. I majored in apparel design & merchandising so I think subconsciously I'm just naturally drawn to & attracted to men who dress really well. I realized there were times when my friends were into a 'hot guy', and I didn't even give those hot guys the time of the day because their dressing was pretty much atrocious. with that being said, having a good dress sense doesn't mean wearing expensive clothes & shoes etc.
I think Guy B would catch my eye. Who's to say average to someone may strike someone else differently. I think the way a guy dresses is of somewhat importance, because I'm sorry, but guys that wear their pants below their rear and have their boxers all showing- is a real turn-off for me. But guys with a sense of style and maybe even a little class is so sexy!
Hm. Here's my answers to your two questions: Well, personally, I'm a hair girl. I like something that's long enough to frame his beautiful eyes, and to run my hands through --a bit shaggy, but clean shaggy. I also tend to go for blond guys (but I've had crushes on redheads and dark haired guys, too. My biggest crush in high school didn't fit most of my criteria, but he was charming, had amazing eyes, was kind, could sing like an angel, and was nice to me.)
As for dress sense, I'd go with clean (not filthy dirty, or miss-matched patterns, or stuck in single decade), and clean shaven. These show me that the guy takes care of himself.