I use the white paper gaskets. Been on the same set for a long time now with no issues.

A good seal is all about getting the header sealing surface straight and true. My hooker headers have a welded bead at each port and I took a marker and colored each bead and then took a wide fine tooth file and carefully worked each opening in a criss-cross pattern until the marker was gone and everything was nice and level.

I have used copper rtv in the past, but I don't have any in there right now. Keep an eye on the bolts after installing as they will loosen up a few times.