What kind of line should I use to fish a Pop-R?

Flouro sinks, so it's not good.

Braid is too visible.

That leaves mono, or a copolymer line.

I like Sufix Elite.

As heavy a mono as you want. Line size really doesn't matter with TW's.

I use 15 lb P Line CXX, but if you're fishing around heavy cover, you could go much heavier.

I use 14lb Suffix mono.  Still allows plenty of action for the popper and keeps the bait floating on top.  Suffix casts great.

I use 12 lb. Sufix Elite.

Mono is always the best with poppers. If your not around heavy cover, you can use 6 - 10 pound test. If there is heavy cover, I would go with 14 pound or even heavier. Original Stren is probably the best mono out there.

I've used 10 and 12lb Gamma Co-Poly and have been very happy.

As mentioned before not Fluoro because it sinks and I wouldn't use braid because of the no stretch factor on a treble hooked bait. So that only leaves mono.

I like YoZuri Hybrid for poppers but braid for just about any other topwater.

30# Stren Super Braid with no leader for poppers because it floats.

I have found braid takes away from the blooping and blipping actions of a popper, and it just makes a weird splash instead of the plop that usually triggers strikes. Go with mono all the way.