I'm a huge petrolhead, and really enjoy Forza. But both Forza and Gran Turismo almost seem a little sterile at times. Need For Speed Shift 2 handled appallingly, but the sensation of speed, and the little effects like rubber marbles forming on the circuit , added the brutality of the crashes made it feel more exciting at times. It also has better real world circuits than Forza.
Shame the handling was wonky. Race Pro is decent for realism, but the graphics and general presentation are sub PS2.
I'd love a decent PC for proper racing sims, but can't afford one at the moment.