Boy, this might be more difficult that the desert island thread going on elsewhere. 5 planes might give me to many options.
1) Corgi Apollo Recovery Sikorsky - Looking for a Saturn V model helped jump start this whole thing for me. While it's true this is not a full Saturn V, but the diorama knocks me out.
2) Finnish Gladiator diorama. I love the Corgi Gladiator and have this set up on my desk with a revolving bunch of winter camo armor. Putting German, or Russian armor with the diorama might not be historically accurate, but it fires up my imagination. (This might count as two models since I have at least one tank with this diorama at all times.)
3) F.O.V. P-40b - A Pearl Harbor plane and a beautiful bird.
4) Hobby Master Lexington Pre-War SBD - I have to have an SBD with me. My collection wouldn't feel complete without at least one.
5) Corgi Doolittle B-25