Are you asking which finish for the guides? If you're looking for a general epoxy for the reel seat and grip, I use Flex Coat's 5 Minute epoxy. If you're looking for guide finish, there are a number of options. I use Diamond II
and like it, if you get it also get the self-sealing insert kit. Here's a review
I recently read on it. As for other options, JS Stockard
sells a number including Flex Coat and ThreadMaster. I'm sure others will chime in on their preferred finish.
Whatever one you get, just be sure to follow the directions that come with the finish and measure carefully. If you have questions ask them on here, do a search for your finish type to see what others have said. Time spent carefully coating your thread wraps is well worth it. I have the top two sections of a 5wt turning right now and am feeling pretty good about how it's turning out...