Milwaukee M12 FUEL Cordless 6 in. Random Orbital Sander

This is definitely the expensive option, but if you’re doing extensive bodywork—especially something like stripping, prepping, and refinishing an entire car—I think this is where spending the extra money starts to make sense.
 
The 6" pad covers more area, the sander is lightweight and designed specifically with automotive paint and bodywork in mind, and the variable speed control gives you more control when moving between different stages of the job. It also connects to a vacuum, so you can pair it with something like the Giraffe Tools retractable vacuum for a much cleaner sanding setup.
 
For occasional projects, I wouldn’t spend this much—the less expensive Milwaukee sanders will get the job done. But if you do a lot of bodywork or want to buy one serious sander and not feel like you need to upgrade again later, this is the one I’d invest in.