Spray paint works fine if you can find the color you want and it's fuel proof. One trick is to put the can in warm water for about 10 minutes before spraying which makes the paint flow out a lot better.
As has been stated, airbrushes are for fine work. I have 5 and use them for my display models or small parts on my R/C models. I had a badger 150, but it started springing leaks all over after about 20 years. I just bought a gravity feed Campbell Hausfield gun from Home Depot and I like it A LOT better than the Badger.
Klass Kote has recently come out with colors that are supposedly close to primary colors (I don't have them yet, so just reporting what I've been told). What that means is you can mix any color. Previously all they had were "dirty" colors. For example, their yellow had a lot of red in it. If you want to make green, then you mix yellow and blue, but because the yellow has red, you ended up with all three colors which makes dirty green or possibly even brown.
Anyway, the point being that if you have the right paints you can mix not only any color you want in any quantity you want, but you can also reduce it to spray properly at your current climatic conditions. Some days you need more reducer and other days you need less. Spray cans are set with what they give you and they don't always spray properly.
Of course if you live in a place that has the conditions stated on the can on any day that you want to paint, then it's not a problem.
My advice is if you plan to paint a lot of planes then buy your own equipment. If you plan to paint the occasional cowl, then buy spray cans.