Well, I haven't really played that many racing games, just cause (no pun intended) it's hard for me to find something that I can really enjoy. I love the Burnout series, my favorite one being Burnout 3 Takedown. I've played Need for Speed, it's good and all, but not something I absolutely adore playing. The experience would probably get better with better equipment, like an actual racing wheel.
But Burnout 3 will probably remain to be atleast one of my favorite racing games for the rest of my life. B3 is unfortunately not on PC though, which really sucks.