Ah! this debate brings me back to my Color Computer days! For those that don't know the CoCo had a 6809 processor that had a 8 bit Data bus and a 16 bit Address bus, so everyone debated 8 or 16? I am sure those with the Dragon know what I am talking about as the dragon was essentially the same computer as the CoCo.
Yes, its off topic...
The Sega Mega Drive is stated as 16 Bit console (Actually the first 16 bit console), while the first 32 bit console is the Amiga CD32.
The Mega Drive have very similar architecture to the Amiga 500 - ~8MHz CPU, hardware sprites, soundchip etc.. The Amiga CD32 is close to the hardware of the later X68000 computers.
Commodore 64; Atari 800; Sega Master System; Nintendo NES; Apple II ---> 8 bit.
Amiga 500/600/1000/2000/CDTV; Atari ST; Sega Mega Drive; Super Nintendo; Apple IIGS ---> 16 bit
Amiga 3000/1200/4000/CD32; Atari Falcon; Sega Saturn; Sony Playstation; Apple Macintosh Quadra ---> 32 bit
microAmigaOne/AmigaOne XE/SE/Sam/Pegasos ---> 64 bit.
