Koh Gen Do from Stormy's was good, but pricey.  I have some Egyptian cotton from 
madvapes that's OK and it was cheap, but not so great a 
vape.  Sally's cotton coil in the big box is  good.  I have a Graham Cellucotton coil (big blue box) in my cart at Amazon right now (100% Rayon) for about $11.  I'm just waiting for something else I need to add to the order before pulling the trigger.
I stopped at Sally's the other day for some Rayon coil, but all they had was the $1.49 bag of Cellucotton that's actually cotton.  The bag says 100% cotton on the back.  It was pretty lousy for wicking, even after I pulled my KF3 apart and rewicked it twice, thinking that I used too much or too little and screwed up the wicking.  I got dry hits and weird flavor both times.  I went back to the Sally's big box of cotton coil and flavor and vapor returned.  Go figure.
Still waiting to try Rayon when the Amazon box gets here.