Easily the fourth gen.

5th or 6th gen

5th gen had oot, mario 64, ff7, wipeout, need for speed, mgs, half life

6th gen had gta3, burnout, ssx, ico, sotc, okami, jak and dexter, ratchet and clank

My brain says PS2 era!

Bu t my heart is with you!

Gen4.

Though I think answers are determined more by when you were growing up and/or gaming the most. 

As a former PC-only gamer I don't think in generations but in years or decades.

Late 80s to late 90s
(MicroProse, Lucasfilm Games/LucasArts, Sierra On-Line, Dynamix, Westwood, Bullfrog, Interplay, Sir-tech, SSI, New World Computing, Access, Ensemble Studios, Blizzard, Bioware, Black Isle, Maxis, Origin Systems, Looking Glass, Ion Storm, Blue Byte, Ascaron, Psygnosis, DMA Design, Infogrames, Delphine, Acclaim, Accolade, Parallax, Spectrum Holobyte, id, Valve, Apogee/3D Realms, Epic [Mega]games and EA)

The golden age of RTS, TBS, point&click adventures and building, economic, flight and space sims.
The heyday, downfall and resurrection of western RPG.
Also of course the rise of FPS - unfortunately.

This generation shits on everything else.

Sixth gen. Oh how Sony spoiled me with the PS2.

Hell they're doing it again with the PS3!

For purely singleplayer games I'd go with the 6th gen however if you include multiplayer games 5th gen takes the cake. Smash Bros, Mario Kart 64, Goldeneye, Bomberman 64, Star Fox 64, and Pokemon used to rule my life.

this gen because now i know what i am doing not mindlessly playing an game. 

Fourth, by far