the e36 chassis is the clear class winner in your choices offered. plus there are alot more spare parts which are reasonably priced when you do need them over the e30 and e34.

the e36 chassis has a much larger production run rate then the other 2, plus the m3 parts fit on the non m3 cars. fenders, doors, hoods, etc will be easier to get/replace when you do replace them from racing or going off track.

plan accordingly within your track/racing budget. the more track time you see, the more you will need spares. don't be short sighted and think once you finish building the car, you are done... it don't stop there...

also, with 4-5 years of track experience, its time to get more serious with safety equipment since you should be driving much faster now... cage, shells, harness, fire system, etc...

imo, there is no such thing as a dual purpose track/race car and a street car. there is only one or the other. everything in between is a compromise of comfort, safety, and performance.