Definitely 6th generation. Played the GameCube, Gameboy Advance, and the PS2 which had by far, the best game libraries combined compared to 7th and so far the 8th. As for the 5th generation, I only somewhat experienced the N64.

has to be the sixth :D

I would say 5th gen closely followed by 4th gen.

Reason: 5th gen had two great gaming systems that I owned in PS1 and N64 with very distinct gaming experiences. Local multiplayer heaven on N64 and great single player experiences on PS1 (Allundra, Resi, FF, BoF just to name a few).

One console in the SNES, even though on its own maybe superior, cannot match that, especially the local multiplayer.

5th of course.

Its the one that brough the most innovation and the bigger variety of gaming experiences.

I went with the sixth gen overall for the simple reason of variety. While the most recent generation had more epic games with the likes of Fallout 3, Red Dead Redemption, Mass Effect the variety died once games started costing as much to make as the entire Lord Of The Rings trilogy to make. Games have got more complex, more nuanced, and objectively better in the seventh generation, but they've also become homogenous and repetitive in ways I can't stand. Almost everything is either a first-person shooter, third-person shooter, 3D brawler, or an open world sandbox game (which will likely share a lot in common with either third-person shooters, 3D brawlers or both). Take a look at the sales for PS3 and Xbox 360. There's nothing really that I can see that's sold more than 2 million copies, that doesn't fit that description at least a little bit. Even our RPGs became very "shooty" (I'm looking at you Mass Effect). By contrast look at the sixth gen.

We had the 3D brawlers with the likes of God Of War, Devil May Cry, Dynasty Warriors, Ninja Gaiden. Every style from killing waves of mooks to deep and difficult challenge. We had plenty of FPSs with the likes of Call Of Duty, Half-Life 2, Halo, Metroid Prime, Doom 3 etc. third person shooters didn't really get big till Gears Of War but the sixth gen had a few good ones like Star Wars: Battlefront 2, Max Payne, Splinter Cell and the Hitman and Tomb Raider series. The open world sandbox genre wasn't as big either but with GTA: Vice City and GTA: San Andreas we had plenty. There was also Spiderman 2, Shenmue, and Mafia.

So that's the popular genres of today covered, but what about the rest? 3D Platformers there was Ratchet & Clank, Psychonauts, Vexx, Sonic Adventure, Super Mario Sunshine, Jak & Daxter and so many more; what did the seventh gen have outside of the Wii which often ruined perfectly good games with waggle physics. Nothing really. Then there's survival horror. The sixth gen did survival horror so well as we saw both Resident Evil and Silent Hill reach their peaks, then there's things like Eternal Darkness and Fatal Frame, modern survival horror outside of indie-games are just action games with more gore now, there's no horror and no worry about survival either for that matter. RPGs are even more polarising. We had such a range in the sixth gen, with Final Fantasy X, KOTOR, Persona, Diablo 2, Golden Sun, Pokémon, Deus Ex, Neverwinter Nights, Skies Of Arcadia, The Elder Scrolls series and more. This was the time to love RPGs. Consoles, handhelds, PC, everything had them. Hell this was back when MMO's where decent, back when it was a challenge and not filled with douches. Everquest, WoW, EVE Online etc. all started early to mid sixth gen. In fact, if you like an RPG from the seventh gen, it's likely a sequel to a sixth gen franchise. There where smaller niches that don't exist now too, like extreme sports games. I loved the Tony Hawk's series and it reached it's peak on PS2, the first Guitar Hero (before it was bled to death) was PS2 also. Hell even the best of PC gaming falls into the 1999-2006 bracket that was the sixth gen. Everything from Starcraft, Civilisation 4, The Sims, Rollercoaster Tycoon, Sim City 4, Total War and more.

I love the forth generation, I grew up on my Mega Drive and early PC gaming. The fifth generation did a lot, with the PSOne having my favourite games of all time with the Final Fantasy franchise, and the Sega Saturn keeping niche arcade gameplay alive, but once the Dreamcast came along we had a successor. The seventh gen has probably most of my "top 20" games, simply because of scope. All in all though, the sixth gen I think is the best we've had yet, and I hope we can go back to that kind of range in the eighth generation now that chasing "better graphics" is resulting in diminished returns.

toss up between 6/5th.

That's why you don't appreciate the 4th generation. SNES/Genesis were awesome, they perfected and expanded upon so many NES IP's. Zelda on NES was ok, but ALttP and LA were simply amazing. Plus remember, Pokemon is technically a 4th generation game, since it released on the Gameboy, and not the Gameboy Colour.

If I had to order them, I would say

5th - Best Multiplayer (N64), Amazing Single Player (PS1)
4th - Best Single Player (SNES).......spawn of Mario Kart
6th/7th gen - tie (same reasons as you). I like 7th better, but the 6th was more revolutionary (Metroid Prime, Resident Evil 4, and GBA is probably the best handheld ever)
3rd - Borth of gaming, but most games don't have saves!

the fourth
love me some Sega Megadrive

4th gen.

Fifth gen for me, N64 holds a special place in my childhood. So much MP fun.
Second place would be gen 6.