8Bit NES for me. that was the most fun- I mean, the graphics looked like ass compared to the 16-bit systems, but by the time they came out on SNES and Genesis all the game-genre's were getting reused + resued so many times that the novelty was starting to wear a little thin. Sure the tech was more exciting, but no way did I get as whole-heartedly involved in Sonic, Mario World or Zelda LTTP as I did in their 8bit counterparts the first time around, when they were new.
Not to say that those games (16bit versions)weren't still some of the most enjoyable games I'd ever played, I'll just never forget the feeling I got playing Zelda, SMB, Castlevania, Metroid the first several months I got my hands on them.. Ninja Gaiden, Mega Man, Bionic Commando, Life Force, Contra, Punch Out.. A lot of these games are still extremely fun to play today. I cant think of any games that have ever been so interesting, novel, captivating since (audiovisuals notwithstanding).. see what I'm sayin'?