Tough choices considering the fact that BMW had some lovely products.
Id go with the E30, 333i, 325is E36 German Spec and the E60 Motorsport, Individual(think they came out in 2003, not sure)
E39 540i M was awesome I thought - very scarce though. But for me the E39 M5 is still the nicest. I think that era was when BMW's styling was at its best - E39 and E46 both stunning ranges!