Many people swear by the simplicity of a single-action brush and there is absolutely nothing wrong with that. 90% of the abilities of an airbrush are in the hand holding it. I am not an expert airbrush artist and I need all the help I can get, hence my preference for a double action brush. The immediate control that you have over the paint volume is well worth the difference.
Second, since you are just starting out with an airbrush, the simple act of pulling back on the trigger to change the paint volume is not going to add much to the learning curve. Instead of stopping what you are doing and fiddling with the adjustment screw on the back and then trying to pick up where you were painting, you just move your finger slightly.
Third, since you are going to use canned air your air pressure is going to be constantly changing. As the air is released (actually I think they use CO2 and not actually air) it chills the can. The can gets so cold that ice forms on it. This causes a decrease in pressure which is normally compensated for by increaseing the paint volume. With a SA brush you WILL be stopping every few seconds to adjust the paint volume. Sitting the propellant can in a dish of warm (NOT hot!) water helps alleviate this, but it is still a problem. Been there, done that, never again.
To narrow your choices down, I have a Badger 100 and 200 as well as a Thayer and Chandler Omni 3000 and 4000. The vast bulk of the time when I reach for an airbrush it's my Omni 4000. It is a great general-purpose brush and would do anything you want for a long time to come. My second choice would be the Badger 100 since it sprays a slightly finer line.
But, in all fairness, if I'm just spraying a single color over a large area, such as when spraying a coat of Future, I use my Badger 200 with the medium tip. It does still have its uses and doesn't just lay in the box.
My advice would be to not over-analyze this decision. You aren't purchasing a car, just an airbrush. Get the 200 if that's what you prefer, and if you decide you need some additional capabilities there are other alternatives available. I personally prefer a double action brush, but many prefer a single-action. It is just a preference and I'm not trying to force you into my way of thinking.