The FM3a would complement the FA or the FE better than the F2AS. That said, unless you're looking for something that has a mechanical shutter in manual, the FE2 is otherwise pretty much identical to the FM3a, looks less funky, and is about 1/6 the cost of the FM3a. The FM3a back and the focusing screens for the FM3a fit perfectly on an FE2.
The F2AS is a nice camera (is my main camera these days, although, I've been using my F more frequently lately). If you're looking for a mechanical camera with a very accurate meter and don't intend to do a lot of flash work with it, the F2AS is an excellent choice.
F2AS, F FTn, Nikomat FTn - John Laughlin Photography - nature photographer