I think everything is a factor when it comes to keying
The framing of the shot (wide, medium, close)
Wardrobe and skin tone
Resolution of camera
The shutter angle
Frames per second
Uncompressed color (4,4,4)
Most things are both asthetic and technical considerations at the same time.
In my opinion resolution and color compression from the camera are a major factor.
Wider full body shots are harder to key. Minimize any green spill on the subjects for clean motion blur key.
Frames per second is really determined by the project frame rate and if its over or under cranked. We did a 50fps PFR a few months back with a red epic. It was decent to key but in my opinion motion looks better at 25fps or 24fps PFR (It was a european project projected at 50p)
Shutter is also both a technical and aesthetic call. Technical consideration of lights beings used, exposure time, and the aesthetic is the desired amount of motion blur. You can still accomplish great keys with heavy motion blur if it was shot with a decent camera and proper set up. I’ve had great results keying 4k red and 3k alexa footage.
I would say along with a great compositor you need a great DP. Lighting ratios are important for a good key.
On some films where I have done only vfx, post production ends up cutting down the image size due to the amount of data before we receive dpx or whatever. Unfortunately that takes away some of the ease of keying. On my own projects I always key with the full resolution sequences and uncompressed color, its a much cleaner key. Having equal color to luminace per pixel is the key.