I know pretty much every guy Ive ever met or known has loved my curls lol.
I think it doesn't matter if its straight or curly or wavy. As long as its soft, not frizzy, and a nice color, healthy and taken care of with a bit of length, I think thats what guys like best. Especially if it smells good lol guys love when a girl's hair smells delicious.
I think some guys like to run their hands through a girl's hair too, so in that case curly wouldn't be good lol.