I agree that it depends on the horse's mane.
I prefer a long flowing mane! But not all horses are capable of having one. Currently I'm working on growing my mare's mane, it's not super long right now, but it is very silky and soft, and just thick enough. She's also a grulla so has some pretty frosting going on. My mini originally had a very long beautiful mane, but waaay to thick (it was breaking his crest), I accidently messed it up trying to thin it some and ended up roaching it to start all over. My pony's mane is currently left natural, but if I was going to do something w/ it I'd roach it. It gets about 4 or 5 inches at the top and bottom, but the middle is only about 3 inches, and instead of laying flat on her neck it sticks out, I've had about 3 horses like this and don't see much more to do then roach it since it refuses to grow any more then that. I also recently roached my family's other horse's mane, his is normally not to bad, alittle thin, but good otherwise, but recently it'd been getting alittle unruly, it had desided to spit in the middle and fall on both sides. I could have work to tame it back where it belonged, but didn't really feel like putting in the time and since no one else seemed overly interested in working w/ it, and I wasn't having much luck keeping it clean (heading into cold weather, so no more baths either (white mane)), I desided just to take it all and worry about it next spring.