NFS Shift/Shift2 are some of the Most fun racing series games on the market.
Gran Turismo spent 7 years developing... Garbage. Same shit as it always was, menus sucked, the driving is dry and emotionless. I loved the Gran Turismo franchise and I own every single GT ever made. But I am truly disappointed in this game we waited som long for.
Shift 2 on the other hand is not as realistic but it's realistic enough to be endless fun. I'm not a NFS fan at all, but the Shift series is amazing.