I have tried a bunch of hobbyist type guns. Guys with experience and skill can get a great job from a crap gun.
I am not one of those guys.
So far my limited experience says this works great for filler primer. https://www.harborfreight.com/33-oz-lvlp-general-purpose-air-spray-gun-61455.html
I have a now discontinued devilbiss flg 3 that i spray base and have sprayed primer and rustoleum with. It did nto atomize the cheap clear I was using very well.