Hurricane, and if anybody ever wants to offer me a Spitfire flight, I'd not turn it down.
Supermarine Scimitar - for the sole reason that my Dad used to build 'em.
For me however the fascination is not so much in getting to fly something unique, but in gettting to learn about it. So I'd love to fly and analyse any of the Lympne air race aeroplanes, and having flown two later derivatives, an original Flying Flea.
In recent years for example I got to fly an Auster and an Aeronca Chief, both with an element of flight testing about them, and both needing some days of reading into the aeroplane and preparation. That, culminating in a successful flight and a meaningful outcome is where I get my real kick. Just getting a ride isn't enough for me.
For which reason my real dream is one day to do the first flight of a completely new design, which would mean more to me that any vintage aeroplane - however much fun that is (although have flown the Cub, Stinson, Harvard, Auster, Hunter, Aeronca Chief, and a few others, so have scratched that itch to a fair extent).
Test flying homebuilt and vintage aeroplanes is one of the few things I'll normally do for free!
G