My favorite planes (in no particular order) :
P-38 Lightning (so cool)
P-61 Black Widow (fer shure! The Lightning's badass big sister from another mister)
B-2 Bomber (how can you not love something that looks like the Batplane?)
OV-10D Bronco (little badass)
C-5 Galaxy (everybody loves big. Great plane, was told it was a bitch to work on...)
SR71 (alone, unarmed, untouchable. flying on the fringe of space)
DC-3/C-47 (quite possibly a perfect machine)
P-6M Martin Seamaster (never put into production, a Cold-War jet sea plane, outran fighter chase planes during testing)
Burt Rutan's Voyager (not a military plane, but too cool not to be on the list)
V-22 Osprey (whadya mean, straight up?!)
There are so many, it's hard to play favorites. I'm sure I missed a bunch that should've made the list...