Had my body sand blasted and I did most of my metal work 1st but I'm about done and I was thinking of using epoxy primer to paint the bare metal before I start my mud work but a coworker of mine suggested I use etching primer. Which one u think would be better for protecting metal because I'm going to primer it then do my mud work with rage gold filler then slick sand after I sand blocked my fillers then go into a 2K primer to get my body lines good and sharp and everything dialed in and then seal it. And on to paint

Epoxy! It's already etched from sandblasting, blow it clean and epoxy it quick.

Epoxy.
You don't want to put filler over etch primer due to the acid content.