After thinking about all the games I played as a kid I notice there are a ton of games that I get nostalgic about. Pokemon R/B/Y, Pokemon Snap, TMNT Turtles in Time, Link to the Past, Battletanx, Guardian's Crusade, the Tony Hawk's Pro Skater games, Pokemon Stadium, the Lion King game on the Game Gear, Aladdin on the SNES, a Power Rangers game I can't remember the name of on the SNES, one of the newest games I get nostalgia about is Seek and Destroy on the PS2 which was an awesome tank game...Just too many to count.
But the very first thing that popped into my head was Spyro the Dragon, that series has to be one of my all time favorites on the PS1. It's one of those series that I get nostalgia blinded by, I think it's easily one of the best 3D platformer series of the era. I'm always disappointed to see how bad the games after the original series ended up being (though I did like the Season of Ice/Flame games on the GBA).