Personally I would go for a mini RSP, I believe that of the modern minis these are the best available, but I would want to keep it visually standard if I did so.

Failing that, any pre 94 (thats when they started getting bloated with catalytic convertor airbag etc) cooper is a good bet.

As per above, buy it on condition, not anything else, the single most important thing is the bodyshell, minis rust a LOT, some were getting rust repairs done under their 3 year warranty, even stuff like new sills!