Nothing beats a 1 piece leather suit. 2 piece leather comes in second, Jacket and pants are zipped together. Perforated leather has pin holes which allows air in for increased ventilation. Textiles are next. They don't offer near the protection of leather but are more comfortable. Lastly mesh. Mesh is very breathable yet doesn't do well at all when hitting the asphalt. It's still better than jeans and a T-shirt.
Personally I wear a perforated leather suit when hitting the canyons and track and textiles when putting around town.