Buy the best one you can afford. That way you'll have more time to actually drive it than to be working on it
all the time. It also usually works out cheaper in the long run to buy a decent car to start with. Personally, I would
prefer a car would a good body and decent paint. The mechanicals can be done in stages if the requires it.
Have a good nose around the sills and wheel arches for rust when it comes to looking at the body.
Bear in mind that the Mk1's are around 20 + years old now so there will nearly always be odd jobs to do anyway.
They really are a fantastic car and the spare parts support is amazing.
Racing green gets the thumbs up from me (but I'm biased !!!).
Also, if you are of a young age, check out your insurance before you buy.