Atom's don't have mounting holes, so they are a little more of a pain to mount. Same with RevoNano FC. I just use 2 sided tape on the case for 'Nanos.
Also, you might begin to think about when you would be interested in GPS, RTB (RTH), waypoint flight, GPS flight modes, telemetry, AutoTune, and new feature in general... CC3D memory is full and generally doesn't get new features, but it also only costs 1/4 as much as a Revo/Sparky2. 1/3 as much as a 'Nano.