I plan to use it fix the rust pitting on the body on my 240D and do some exhaust work.
As the OP has said, the requirement seems to be woking on thin steel, either body or light tubing, etc., so that would certainly endorse an inexpensive MIG. But I'd try and not be tempted to save $$ by buying a flux-cored wire-only machine. I've tried one of these, and they do work, but there's a limit to how thin the sheet can be before you really have burn through problems. There may come a time when the manufacturers will address this with better flux compounds, but right now, the heat required to vaporize the flux core is too high for body metal work.
As for brazing, this is fine for many shop jobs, and relatively cheap too, but the problem for body work use is again, the fluxing agent, which will play havoc with your filler and paint.
In my home shop, I have a 220V stick welder, oxy-acetelene, and the gas MIG (which is Metal Inert Gas, BTW). The stick welder is back-up for the MIG, and used for very occasional heavy steel work (trailer hitches, frame repairs, that sort of 1/8" and up stuff). The torch comes out to persuade rusty nuts, and cut muffler & tailpipe bolts. The MIG is used 99% for the heavy and light jobs both.
I built a streetrod over a 14 year period with a MIG, bought locally and still available from Enderfield & Hall, Chicago, called the Practic 120. www.kooltools.com
It doesn't have to be top $$ to work well, especially for home shop use.