look, i hate e36. but if you want a competitive track car, they are better than the E30. buy a 325i or 328i Manual coupe, and you have a great competitive car right out of the box. The M50 and M52 engines are both fairly bullet proof as long as they aren't allowed to over heat, which happens quickly and unexpectedly, youd do well to change the cooling system completely on that car.
if you want fun though, a car you can slide out and you dont care if you are the quickest, an E30 would be the way to go. They are down on power to the E36, and the trailing arm suspension setup is very dated.
im thinking about building a race car seriously next year, and an E36 328i Manual coupe is more than likely the way ill be going, even though my heart tells me E30 E30 E30