I have no idea of usage, I just played them to death when I got them.

ZX Spectrum 80 & 81, 48K, 128k, and 128k+3
Playstation 2
PS-One
Atari
NES
SNES
Powerbase & Master System
Mega Drive
Mega CD
32X
Saturn
Gameboy (da monochrone one)
Jaguar

I still have them all.

The top usage ones would probably be PS2, PS-One, and Mega Drive.

Although the Spectrums I owned were used a HELL of a lot, but not always for games.

I also have had a lot of PC's over the years. Including an 8088 which was 4.?Mhz with 2048Mb Memory, and a whopping 40Mb HDD that had to have its head parked before you moved the machine.