I believe a modern reliable car with a classic appearance to be the ultimate.As kit builder and semi-mechanic, you can bring at least the most important parts with you in the car, like ECU/MAP etc. There are also universal diagnosis testers,, I have a program for my Renault on a laptop, to detect errors, so I can do a check on the road.
I have built-in a 1400cc in the R4, injection engine of a Super 5 and drives perfectly and well arranged. ..
A very classic car or kitcar with low maintenance and problems and little costs is of course best.
Love the mecanic , who comes with the car too