Baldurs Gate on PC! I know alot of people give it credit were its due, but so many people i know never even heard of it.
A more valid response i would say is Star Wars Knights of the old Republic, OMG IM REVAN! was just one of the million reactions/reasons that make that game have a great spot in my list of greatest games of all time!
also Final Fantasy 9, Asherons Call, and im sure i'll edit about 100 more on when i think about it a bit more