I thoroughly dislike neoprene girths. They are slick when wet, pull hair when dry, hold the heat in, and they will gall the crap out of a sensitive horse.
I'm not a huge fan of felt cinches either as I've seen too many sores from where the felt bunched up and created a pressure point.
Personally, I only use mohair or alpaca (generally mohair because it's a little cheaper) string cinches. So long as they are adjusted and sized correctly, I've never had one gall a horse. They wick away moisture and dissipate heat well.
You might look around, but this is similar to what I use. I can buy mine (still 100% mohair) for about half the price at my local feed store in their little tiny tack section. Professionals Choice Mohair Straight Cinch - Horse.com