Agree with all the choices made so far. However I would just like to say that any 935, not just the K3, be it the most basic 78 car right up to the Moby Dick car will always stir my blood like few others.
The WM's of the 80's sould also be mentioned. Little in the way of money yet also turned up with pretty decent cars. they seemed to be there for the love of it, just like me.
Other cars -
BMW M1 for its amazing noise.
Porsche 936, it always looked graceful
McLaren F1, the last road car to win LM, and Ferrari F40 for trying.
The more I think about it, this list could go on & on!