Greatest aircraft ever flown: Hands down--the F-15C. 550 kts at 500 feet, looking for bad guys, trying not to hit the ground, checking six, trying not to hit the ground, oh dark thirty over bad guy land watching red tracers, trying not to soil my armor...as my Bone friend said previously, "Yeowsa!"
Greatest aircraft I may still yet get to fly: the Yak 9, Russia's answer to the P-51.
Greatest aircraft that I won't get to fly: the SR-71.