My thoughts:
1. NES - 90% market share, virtually 99% of industry support, every game was a new IP or an amazing sequel to it. Launched SMB, Zelda, Metroid, Final Fantasy, Dragon Quest, Castlevania, Mega Man and on and on.
2. SNES - Could be number 1, but I give that to NES because of originality and market dominance. SNES was everything great about NES but better, with massive graphics and sound leap adding to the story elements of titles like Final Fantasy. An incredibly diverse lineup of AAA games, the last console to be truly the home of Nintendo 1st party and all 3rd party, most of which was exclusive.
3. PS2 - The strongest market leader after NES, it had the same level of complete 3rd party support and diversity of software. Lacking the Nintendo 1st party support, but it did have some exclusive or at least timed-exclusive special 3rd party titles like GTA3-VC-SA. 3D graphics done right.
4. PS3, XB360 (tie) - The jump to HD was very impressive. I give these systems a tie because the experience offered by both was very similar. 90% of the libraries are the same, in particular the big-selling key franchises like COD, GTA, AC, FF, ME, ES:O, etc. The games that defined the generation were on both consoles, while the 1st party games were more complimentary than market leaders.
5. N64 - the 5th gen is my least favorite, with the crisp 2D gameplay of gen 3 and 4 giving way to clunky polygons and poor controls in a 3D environment. Even at the time of release I longed for the polish of the previous consoles. That said, the jump to 3D and improved graphics and sound did offer amazing new experiences. It's a worthwhile debate as to which system, N64 or PS1, provided the definitive 5th gen experience. I give the nod to N64 because of it's superior game-rendered visuals and landmark titles. PS1 offered properly executed advantages of the CD format for the first time and a larger library with full 3rd party support, but few titles hold up to the elite N64 games. Zelda OoT, Mario64, MarioKart were breath-taking at the time, and also stand the test of time to look great today.
