[jtagger19]

I had the same Q when i was getting my first nordson gun
I'll tell you what i was told

tribo guns charges the powder better but it coats at half the speed of the corona and you can only use epoxy powders or tribo treated powder .

so I bought a corona and i have never had any problems and i shot any powder with it .
the only draw back i have seen is that metallic powders wear out the resistor on my gun so i just keep a spare around .

also try to get a gun that you can get replacement parts easily