Trotter, a buddy and I played F-18 Hornet 2.0 to death over a LAN when I was 14 years old.
Here are the flight sims that made the biggest impact on me, in semi-chronological order:
Flight Simulator
Red Baron
Their Finest Hour
Falcon 3.0
Warbirds 1.1-2.6
Currently, I have 3 flight sims on my computer: Aces High, Il-2 1946, and Falcon 4.0 AF.