I like the 10’ closed loop yacht reins or flat nylon woven reins. The 8’ loop is standard length and way too short.
I do not like cotton reins- they are soft but in AL they get GROSS with sweat and heavy and nasty. I have a pr, they get used only when it’s nice and cool LOL.
My SO loves is skinny little yacht rope el cheap Stacey Westfall Weaver reins- they have little water ties for safety/AKA the end will break off the rein if the horse got loose and stepped through the loop- but they are so small in diameter they’ll hurt your hands if you ride w/ contact.
My personal fave? The wintec reins, padded and non padded alike.
at the end of the day some sort of beta or biothane rein is ideal for the easy clean up and no care other than rinse 'em off.