I did the Lightning - there really is no choice (cost aside) - if you want to fly a Hunter you can do that anywhere - you can only fly the Lightning at TC. Also, think about the future - Hunters will be around the world for many years - I hope it won't come true but I doubt the Lightnings will be around in a few years' time, be it either for regulatory or maintenance reasons.
Whilst I was at TC another (non-pilot) Brit was there - her husband had bought her a flight in the Hunter, Buccaneer & Lightning as a birthday present (I almost would've married him myself). Even after flying the Hunter and Buc, she said the flight in the Lightning was simply so much more incredible and totally incomparable. I'll never know though, but am very happy with my decision!
I always regretted never having a go on Concorde - at least now I've been supersonic a few times (once accidentally at 500' along the coast!) - the marginal cost really isn't that much if you're going to do it anyway!