I like just about any airplane (as defined by FAR 1 - "an engine driven, fixed wing, heavier than air, aircraft that is supported in flight by the dynamic reaction of the air against its wings"). Therefore, my favorite airplane is the one of which I am making a model of (currently its the HS 129, the PT-19 and a JU-87D8).
Don't do helicopters, just don't care for them because:
A. They don't fly, they're so ugly the earth rejects them.
B. There are entirely too many parts going round and round and up and down at the same time, at high speed.
C. When the engine quits, it assumes the glide ratio of a brick.
D. They will fall on you and if you paint them OD green, people will shoot at you and they will still fall on you.
lol