Age and amount of hair plays a huge part in this, from my experience. There is also a little bit of a paradox going on here in my opinion as well.
I think innately women actually prefer chest hair. It's a manly and therefore preferred trait, like facial hair. However a bare chest has become the new trend due to these Justin beiber like celebrities that look like they're 12. Look back to old photos from 30+ years ago, all the men had tons of chest hair and the women loved it.
For the longest time I ASSUMED that a bare chest was sexy, just because it seems to be the new "in" thing. But now that I'm older, I realize that either bare or hairy can be sexy. I think some hair is sexy because it's a very manly characteristic, and since I'm attracted to men, manly characteristics are what are attractive to me. I see how the aesthetics of a bare chest can be preferred, and I'd date a guy with a bare chest, but I think some chest hair is sexy.
On that note - too much chest hair can be a turn off. As long as the guy keeps it looking neat, it's perfectly fine.
Doesn't really matter but some chests look better with a little hair. Not to much not to little?
A little, not a lot. My guy friend is pretty much a bear. He has hair everywhere. When he's in a swim suit, he's completely covered. His beard goes to a neck beard which connects to his chest hair which connects to his happy trail. It also goes from the nape of his neck to his shoulders, arms, and back. And his legs are hairy too. I can only assume he's hairy everywhere else too. My boyfriend has a little chest hair and since he's blond, you don't actually see it.