I guess I really am out of touch, or something. I'm REALLY surprised at all this PS2 love... the PS2 doesn't even enter into consideration for me. I don't know if I can think of a single PS2 game I'd put in my top 25 games. Oh, maybe MGS2.
For me it's a close contest between the SNES and the PS1. There are actually a lot of direct comparisons. The SNES had FF4, FF6, and Chrono Trigger - the PS1 had FF7, FF9, and Xenogears. The SNES had SM, the PS1 had SotN. F-Zero vs Gran Turismo. As far as differences, the SNES had a bunch of great platformers. And it had LttP. But the PS1 also had stuff completely unlike anything on the SNES, like Silent Hill. And I think it had more good RPGs, like Suikoden 2 and FFT. It's basically a tossup.
I think the rest of my top is NES, GBA, and 360 in some order. Even though I play the PS3 more than the 360, a lot of the games I've liked for it also are on 360, and lots of times they come out first there (like Braid). The NES was low tech, but still lots of fun - and probably still the biggest jump in gaming technology from its predecessors - I couldn't play an Atari game now, but I can still have fun with NES games.
1. PS1
2. SNES
3. NES
4. 360
5. GBA
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I made a living on time trial blowing myself off to cross the finish line at ludicrous speed. -transience