I am always a bit biased against forza as my steering wheel did not work with xbox so when comparing it with ps3 games the latter always came out on top in terms of playability
Forza was good with the choice of cars and modding bit, but gameplay lacked and the season challenges were weak with no real progression just a few more points so you can go and modd some more cars, which got
after a while
Cant comment just yet on gt5 as still doing the licence bits, but purchased a 2nd handa mazda mx5 for 16k ish and looking forward to starting my career