I think paper leader is less durable but it's easier to thread IMHO. Plastic is kinda slick, so you need more pressure on the windings to keep it from slipping. I used to always use paper because it's also easer to write on ( tails out, length before recording etc.) and if a bit sticks out from the wind, it doesn't make as much noise as it goes around. I've been using plastic lately though. I didn't know they still made paper. Where'd you find it?