The "best" spray guns for glazing are those used by Steven Hill and demonstrated in his workshops. The Devilbiss HVLP sprayers and the DeKups system for holding glazes work great. The cup system can store glazes overnight, and can be rinsed out to use again and again. These sprayers and cups are sold through automotive suppliers. Google the name "Devilbiss" or "DeKups".
You can view this process on Steven Hill's video..."The Surface Techniques of Steven Hill"....this is the best process I have found.
You will need to purchase an adapter for each spray gun to fit the DeKups system ( DC-11). It screws onto the top thread of the spray gun, and twists into the cup system.
Also, you will need the correct fitting for your gun to attach to your compressor hose. These can be purchased at Lowes or Home Depot or any hardware store.
This system has truly changed the way that I glaze.