I bought the Logitech Driving Force GT last friday and I'm very happy of it so I recommend it. But like it's been mentioned here before, the pedals are very lightweight. Before the DFG I had a Thrustmaster (rumble force something, cr*p tbh) and the pedals were very heavy so it took a while for me to get used to the new ones. I guess you haven't had any steering wheel yet so you won't take any notice. So if you have the money, buy a Fanatec or G25/27, if you don't then surely the DGT
When i brought my wheel i think it took around 2 seconds off my times possibly more, i found you can take just about every corner faster with a wheel. the wheel is a little more forgiving in the sense that its easier to correct mistakes like missing an apex or running wide. not to mention it increased the enjoyment of the game.