With brad nailers and staplers, size is usually not an issue. When you need a larger compressor is when you are spraying a finish. it is not the PSI that counts, it's the CFM that counts. For finishing, you need a larger volume of air and sustain it.
Again, just about any of the small compressors will run your brad nail guns. the brad nailers require about 90 or less PSI and virtually not much air volume. Air sanders usually require about 4.5 to 5 CFM at 90 PSI.
Tony B Retired woodworker, among other things.
"Strive for excellence and settle for completion" Tony B