i've used syphon, hvlp and pressure pot guns.
each have their uses and pro / con for different applications
furthermore.. many people have a favorite.
foir farm use? hit harbor freight.. get a 15$ gun and associated regulator.. don't use a oiler or a line that had an oiler on it.
practice on a piece of old car hood or cardboard.
clean the gun after use.. you can do some good work with a cheap gun with a lil patience.