I'd probably have to go with the SNES. Overall, that particular console war was more about content. While the Genesis and other Sega consoles had some good games in multiple genres, they just didn't speak to people as much as the SNES's wider range of games. Not only that, the SNES and most of it's games were more available, and cheaper too, which makes a big difference whether you were a kid buying games or parents buying games. What really did it for me was the RPGs. The SNES had a vast array of RPGs, almost all of them amazing, while Sega only ever launched one set of RPGs that really spoke to me. (The Lunar series) Surprise surprise, the Lunar series jumped the ship on Sega way before Sega got out of doing consoles.
The problem with Sega was always the idea that Sega had some very innovated technology, and often it released this technology before anyone else (and before it was ready, even). They would release a system that was ahead of it's time, but for a price that was way ahead of it's time. Then their competitors would release a cheaper system that corrected Sega's mistakes, since they were able to see how the market treated the new consoles. The SNES and Genesis (Plus attachments) is a great example of this. SNES largely won out due to popularity, cost, and range of games. I might also speculate that Sega's rather.... limited game pool often game from the system's tendency to make design more difficult. Sometimes being the most advanced doesn't work in your favor, when it makes you choose between making an okay game because of the extra work to get it on an advanced system, as opposed to a great game by using that extra time and effort on actual content. That's only speculation though, based on both the time period and what Sega has done since.