Yar, that's a toughie. If I could own an aircraft it'd be a PBY or a Grumman Goose sort of thing. If I could fly any aircraft. Well, now you are talking. Is it a balls to the wall ride like an EE lightning or an F-105? Or something elegant and an all rounder like a Viper or a Fulcrum?
I think I'd probably go with the venerable F-86 Sabre.