Today's aerosol paints generally have better spray patterns, especially "real" car paint like Duplicolor, than the "model paints" from the old days. It's true that with proper prep and technique, you can get just as good a finish using a spray can as you can using an airbrush.
Using an airbrush correctly is an art unto itself... you have to thin the paint correctly, you have to set the pressure correctly, you have to apply the paint correctly, etc. Using an airbrush does give you the ultimate in control, but it's harder to use an airbrush than a spray can, especially for a beginner.
It all boils down to what you're used to. The airbrush offers more control, the spray can offers more convenience. Either way, airbrush or spray can, can give you an excellent paint job. The trick is using either of them correctly.