A bit off subject, but I'd say the best console purely for having the right technical specs for its time was the PS1. It was affordable and did really well with 3D for the time, which was the next big thing. The N64 was more powerful, but cartridges, as much as I love them, hindered it.

Purely from what was in the OP's post, I'd go with the N64.

If I had to combine the two (balancing the best technical specs for the time and the factors in the OP's post) it would have to be the SNES. I love Sega and actually slightly prefer the Genesis game library to the SNES library overall (although I love both libraries and both consoles) but the SNES was a beast in the 16-bit era. DKC? You really couldn't do that on Sega (without an expensive add-on). I know people bicker about enhancement chips, but they didn't make cartridges all that much more expensive and the SNES was designed to put enhancement chips to use. That, and they're generally a reliable, easy to use console with well-designed controllers.

The reason I put the N64 ahead for the criteria in the OP's post is because it's just as reliable and easy to use, had a bigger innovation in controllers (the analog stick), and it looks a lot better than the SNES aesthetically. Especially if the SNES is yellowed. The guts of the SNES are top-notch but the look leaves something to be desired with that odd gray and purple color scheme. The N64 has good guts and good looks.