The SNESs success in the console war (it sold like 20 million more systems, thats a win) meant that many games on the Sega Genesis never got as much positive attention as they should have. Whether they were not well-known or received a poor rating in light of the existence of competing SNES games at the time, some really good games slipped through the cracks.
Source: N4G PC The Best 15 Underrated Sega Genesis Games