I totally agree with @curl-6 about Donkey Kong Country. It arrived at a time when people were speculating about next gen systems. Unlike now, when people are always looking for what's next, (from where I was sitting) people were happy with companies trying to squeeze everything they could out of the hardware they already owned.
DKC came out and gamer's heads exploded. The crazy part was that it looked/sounded better than games running on more powerful hardware. I'm not sure it was the "game changer" as the first game sold less than 10 million and a ton of those had to be pre existing owners. It just helped aid the idea that the SNES was alive and thriving while the Genesis felt like it had one foot in the grave.
Sega was bringing out stuff like Vector Man and Comics Zone that looked good but wasn't a hit with audiences or critics for whatever reason. Nintendo was hitting with DKC, Yoshi's Island, Chrono Trigger, etc. plus arguably better versions of most multiplats. The SNES just hit its stride at the right time.
That's how I remember it, at least.
