I use a Weaver neoprene Smart Cinch for my gelding - it is so easy to keep clean - that's what I like most. I've had no issues with rubbing.
I use a felt Smart Cinch for my mare - she seems more comfortable with the felt. I have read about the new SMx VenTECH Western Cinches - they feature a ventilated limestone-based non-slip neoprene liner that conforms to the horse and allows heat and mositure to escape and keeps the horse cool and it has all-way stretch - it's about $50 as compared to $40. I've been pleased with the Smart Cinch and I like the neoprene because I just wash it off after each use - the felt is not so easy to maintain - I have washed it but it takes a good while to dry.