I have to go with Need For Speed: Hot Pursuit II. That game had the best graphics out of all of them, had a small R/C cars cheat, which makes all of the cars, traffic, and AI cars into small R/C cars. Carbon is annoying, because it would just freeze after I'm done customizing a car from scratch, and try to do a race. It did not have one scratch on it. Also Need For Speed is just getting worse after NFS:HP2.
Another decent one was NFS:MW, but I hate how much orange is used in that game.