Favorite airplane I've flown: The Seneca I. Friendly, comfortable, reliable. If you count full motion Level D sim time, then it's the 737, even though that airplane is an absolute DOG on one engine.
Most fun I ever had in an airplane: Pitts S2A. Logged .7 in it, and I figure .5 of that was upside down. What a ride!
As a passenger: The MD-11. Quiet, comfortable.