The nitro worked best for me, with excellent results. Downsides, as I sprayed in my garage, were the danger of fire, toxic fumes, the need of low humidity and the smell (neighbors).
Now I discovered the waterborne finish Nitoraqua from Nitorlack, a part of Valresa coatings, Spain. (their partner in Mexico makes finishes for Fender)
This finish turns out to be fantastic. It looks strange and thick out of the can, like wallpaper glue and has to be sprayed with a 2.4mm nozzle.
But it is not flammable, non toxic, little smelly and can be sprayed at almost every humidity and temperature. It dries quite flat with very little orange peel.
I can easily flatten it with 1200 grit! Saves so much elbow grease.
The costs are about the same as for nitro. However, I do not know if they ship to the US.
One downside I found: The drying time between layers is 4 hours. So with 3 per days, it sits in your whole day schedule. But when ready it is quite hard and has a super gloss appearance. This my way to go from now on:
