The Mega Drive had mixed fortunes. In Japan the console was out sold by both the PC Engine and later the Super Famicom. In Europe on the other hand, the Mega Drive fared considerably better. The practically unheard of TurboGrafx was extremely rare and the Mega Drive was able to outsell the SNES, finishing the generation in first place.
However, the success of the console in Europe, and as the Genesis in the States, may well have contributed to Sega's downfall. Two misjudged add-ons, the 32X and Mega CD put a huge dent in Sega's reputation, one so large that the company would never recover.
Please consider donating your old computer / videogame system to Old-Computers.com or one of our partners from anywhere in the world (Europe, America, Asia, etc.).
Watch out for very late revisions of the Mega Drive 1 (VA7). Like most Mega Drive 2s, they were made with significantly worse sound quality than most Mega Drive 1s. This was due to removing the physical YM2612 chip and embedding a YM3438 in the ASIC with the graphics and PSG, but without correcting the audio amplification circuit for the difference in output level / impedance. This can be rectified with a Crystal Clear Audio or MegaAmp audio mod or as part of the Triple Bypass video board.