I like Duracoat a lot. If you have a compressor, get a little hobby air brush sprayer. I have bought stencils from Duracoat, printed some online and cut some from masking tape.
The stencils from Duracoat are pretty sticky. I chose a difficult digital camo pattern for an AR. Looks great, but I'll never do that pattern again. Way too difficult on an AR. Too many hard angles to negotiate.
You can sponge paint w Duracoat too.
I have also used a good quality spray paint. They all seem to stick just fine.