My top 5 would look like this:

1. NES
2. PS1
3. SNES
4. Genesis
5. Atari 2600

For me spots 2-4 are very close, but the #1 spot, the NES, blows all of the other systems out of the water.  It was the most amazing time to be alive as a gamer.  So many new types of games were created: Super Mario, Zelda, Tetris, Metroid, Light Gun games, console RPGs, Strategy games like Nobunaga's Ambition, top down racing games like RC Pro-Am, Punch Out, etc....  There were so many great games that were nothing like I'd even encountered before.  It was mind blowing.  

The biggest thing I want from a game is a fun game that gives me experience that is nothing like I've ever had before.  The NES delivered that far better than any console I've ever played.  Since then I've mostly seen incremental improvements on games that have already made before.  The NES was most innovative system that ever existed and no other system even comes close.  I also owned and played far more games for the NES than any other system that came afterward.  I long for the day when someone releases another system with as many great unique experiences as the NES had.

1.) Snes
2.) PS1
3.) NES
4.) N64
5.) 2600
6.) Dreamcast

7.) Genesis

Never played on the others not mentioned.

I'm going to say PS1. It was the second console I ever owned. I'd love to say the N64 as it was my first...but it just doesn't have the sheer amount of games the PS1 has

I would assume PS1 because it came at a time where most genres were still commercially viable while the technology let developers do things unthinkable before CDs.

N64 for sure. Most people either A didn't have one or B. Just do not remember how mindblowing those games were when they came out. Not only that they felt and played amazing at the time sure, they are old and blocky now. The games still stand the test of time though it had few and far releases the games it did have were mostly the highest of quality compared to the shovelware that was the sony ps1 where it felt most games were a gamble and 80% of them sucked.

Snes a close 2nd imo with just all around great games just not as mindblowing as I remember the n64 being

SNES. Unlike the N64 and PS1 the games and graphics have aged very well and still hold up today. It has both quality and quantity. We still use its basic controller setup to this day.

N64.

This is my answer in all these kinds of threads; "Best of Nintendo", "Best of the 90s", "Best of the Last Century", "Best of all-time", you name it. The sheer amount of game-changing games and innovations is unreal. It also boast a good host of my all time favourites, including my personal #1 and #3. Every system ever has duds, but the big games from the N64 are still fun to play, and are even still among the top of their classes even today. Really the only thing one could argue has faded is the graphics, naturally, but even those still hold up acceptably for the highest profile games.

PS1 . Revolutionary console, with so many great franchises (IP's) made for that one machine. Made gaming popular among adults and younger generations alike. They also released the DualShock with it, which set the standard for all modern controllers with dual analogues, extra shoulder buttons, layout etc.

SuperGraphx or go to hell.

While I love the PS1 and N64, and quite like Megadrive, Saturn, and Dreamcast as well, I have to go with the Super Nintendo as numero uno.

From Super Mario World and Yoshi's Island, to the Donkey Kong Country trilogy, to A Link to the Past, to Demon's Crest, to Super Mario RPG, to new series like F-Zero, Starfox, and Mario Kart, it just has so many golden classics.

And I'm not even an RPG guy; if I was you could add the likes of Final Fantasy 5 and 6, Secret of Mana, Earthbound, and Chrono Trigger to the mix.

Its vibrant pixel art and game design has aged absolutely beautifully, its controller is still just about perfect for its purposes, and it's amazingly well built with my system I got for Christmas of 1994 still working just fine to this very day.

Still the greatest system not just of the 90s but of all time in my book.