If I think about it rationally (a first) I struggle to think of what I would now change to - for every upside there would be one or more downsides. The Zed is a really good all rounder that can be maintained at reasonable cost, is fairly rare, sounds good, goes pretty well and is easy to live with. If I hadn't the Alfas, Caterhams or the Elise I would have always wanted one of those at some point
I had yearned for a Caterham (Lotus 7 as it then was) from about 1966...but I've got that out of my system now. Budget is a big factor for me. Bar one they were £10k or a lot less.... but crucially I have been lucky from a reliability point of view.
If money and sense and life expectancy was no object I would want a 6R4 built to tarmac rally spec.