I think Betrayal at Krondor is the one I have the fondest memories for. A lot of the other older games were ones that I may have really enjoyed at the time, but they had aspects that I would take major issue with if I played them today. But BaK was a rare game in that not only was the story great, but the mechanics and gameplay were extremely well designed. Some aspects might seem a little basic if I replayed it now for the third time, but I would still enjoy doing it.
I prefer to pretend that it's sequel never existed though. Also the bland spiritual sequel set in a different world.