X planes, Luftwaffe jets, ME 163 would be awesome {real cheater holes
}, same for the Huckenbien, Saab stuff{ Drakken, Tunnan etc} Mig-17,21,25, a Horten would be great too.
ME-262 with a single engine{no seriously, I have looked into modding the fuse to hold the engine, seems like it could be done with a weird angle cut pipe and a more tapered bottom aft fuselage} I think it could be done and not look too goofy.
Anything weird, obsolete, experimental. If I see another new kit for an F-15,16,18 I will puke[:'(]
Love em but they are way overdone, especially when there is soo many potentially neat planes to be put into a kit.