I've coated a few handguns using Moly Resin. I like it a lot - quite durable and easy to apply. I prefer the way that it looks over Gunkote (which always appears too glossy to me).
Randy from RD Precision, well known in the tactical rifles world, recently noted that Cerakote is more durable than Moly Resin, but is a much more complicated product to measure, mix and apply properly.
If you are planning to do it yourself, I'd recommend Moly Resin.