Grand Theft Auto. 3/VC/SA are fantastic games, San Andreas Multiplayer is probably my most played game, but GTA 4 is just crap, for so many reasons, i.e. they sucked out all the fun vehicles and added 'Driv3r realism'. I didn't even bother with the expansions.
Also Pokémon. R/B/Y/G/S/C/R/S/E (Jesus, that looks weird) are great games, and maybe the newer DS ones are good too or even better, but I just can't be bothered playing the same basic games over again. I guess I'll never relive the feeling of excitement and eager anticipation I had when I bought my copy of Pokémon blue when it was new out for my old black and White game boy. 'Sadfrog.jpg'.
Oh yeah and after reading some other posts, Medal of Honour. I liked Rising Sun and Frontlines on PS2, but they're just releasing the same things again with 50% more Call of Duty stolen content, and updated graphics. Yawn.