I would keep my mid 90s mbt. It has a nice lugged steal frame, takes racks well if I need to load up, has horizontal dropouts so I would prob build up a second rear wheel fixed / free, even though it's ridgid I find for most off road we have here in the south of Uk I can keep up with most people. So that bike plus one rear wheel and two sets of tyres would give me a tourer, a fixed gear, a single speed and a mountain bike.