What Dewey said. I would skip anything that is ribbed or heavy cotton - so no to the cotton naturals, which I’ve worn at some point in my life and found unbearable. Plus, they’re generally not flattering, to put it politely.
Look for a crispier fabric that feels athletic - I have a pair of Dover Riding Sports that are shockingly nice, and a pair of two of the Smartpak breeches. I’ve also got a few pairs of Tuff Riders that are surprisingly adorable - of course, they’re green and rose colored, but they have a euro seat and good knee patches and they’re durable. I also like the above look of the Pytchleys and the Ovations.
I’ve had pairs of TS that wear like iron and pairs that haven’t. The old school fabric, if you can find it in a beige-y enough color, wears forever. But they’re hard to order online because I swear every pair fits differently.