Porsche 2000 for me:
-Great cars (fully upgraded '78 911 Turbo 3.3l is one of the most fun to drive cars in any game I've played)
-Decent damage model that promotes skilful driving without being overly draconian
-In general a good balance between arcade and semi-sim style, again the handling is forgiving while still not letting you drift round every bend
-Decent gfx
-Great tracks
-Evolution mode feels really nice, rather than progressing from hot hatches up to supercars as in most arcade racers, you are moving through the ages with Porsche
In fact, Porsche 2000 is the only racing game I've completed multiple times I think, with the possible exception of Motorhead.