The paint on my fiberglass, (SMC), hood has deteriorated to the point that areas of fiberglass are now showing. It's getting bad enough that the fibers are coming loose.

To prevent further UV damage, what would be the best primer to reseal it? I'm not sure when I will be able to completely paint the car so I am assuming I will need some sort of top coat over the primer. I'm not sure if there is any primer used by itself that could be considered a long term fix.

I was thinking either epoxy or Slicksand/Featherfill.

So, whoa, back the truck up on this. Loose fabric like that needs more than just going into a sealer or regular epoxy primer. You essentially need to re-resin in those fibers before even thinking about spraying anything. If it is SMC then you either need an SMC compatible resin (Evercoat makes several) or something like West System Epoxy resin. You need to brush on a couple of coats of that to get above those fibers or they are just going to print and pattern right through your primers. Personally I'd go with West and use 2 to 3 wet on wet coats, sand that when dry with some 120, guide coat checking for pinholeing and level, Body Iceing, guide coat again, and THEN seal it all in with epoxy primer and further high build primer.