I don't know how those cameras would fare as aviation cameras - either of them are far beyond my scope of purchase - but people have been taking pictures of planes and other man-made flying objects well, as long as they have been around. Unless the aircraft is flying straight at you or flying perpendicularly away from you, the AF lagging behind the shutter should not be an issue and in almost all cases you would be shooting at infinity so internal lens movements to acquire focus should be at a minimum.
If you are expecting to crop a lot, I guess a camera with higher resolution would be better for you but that also depends on what you are going to do with the image. If you are going to be printing large mural sized prints, higher resolution image would be better but if you are going to print at or below 11x17 or not print at all, even a cropped image from my A7II will be good enough on any consumer grade monitors on the market. I have seen images printed from the first generation Olympus OM-D E-M5 (16MP) at 11x17 and they were excellent.