I own all 3 (Realflight G4 upgraded to 4.5, AFP Deluxe, FS one). AFP Deluxe was my first and the flight model and physics are very good. It's main failing is the POV makes it nearly impossible to tell where you are in relation to the runway until the ground comes into view just before touchdown. This makes the sim virtually useless when trying to teach someone to land. I bought FS One on sale to see if it was any better in this regard and was just very disappointed in the product as a whole. I then flew G4 at a store display and immediately bought a copy. It takes decent hardware to run it...but that's the price you pay for cutting edge graphics and high frame rates. Overall I don't think there is any comparison. Get adecent machine with 2+GH processor, 2+ G ram and stick a GeForce 9400 or better in it and you're good to go. BTW, I just picked up another desktop with better specs than those for $249 because retailers are blowing out their Vista machines in preparation for Windows 7. Check around - there are some great deals out there.