I have used both, and like anything else, it depends on what I am trying to achieve. In using the airbrush, the range of colors available from the various paint vendors are phenominal, whereas, if you use hobby paints, and an occaisonal can of Duplicolor like me, you are limited. I am a replica stock builder, and I have stockpiled various factory colors for future projects. Testors, and Tamiya has made a gallant attempt to cater to the Replica Stock Car builder, but their paint does not compare with the product available from the likes of Model Car World, Scale Finishes, et. al., when it comes to appearance. When I started to do this Chrysler 300, I was going to do it as a Replica Stock. When I shot the Testors' Lacquer on it, the flakes were so big, that I either had to strip it, or build it as a street machine.
When I painted the '64 Chrysler with Tamiya Silver, the finish blushed terribly, even after multiple coats of clear. Fortunately, the finish came to life after polishing.
I shot this Olds442 with Model Car World 1966 GM Fawn. The paint sprayed out of my airbrush smoothly, and without drama.
To each his own I guess. I like both, and everything will depend on what I am trying to achieve.
The Bonneville was shot from the can.