360 controller by far
It's going to probably be the most common one to have good built in support. The analog triggers are necessary for brake and acceleration. The only complaint really is the d-pad, though that doesn't really matter with racing games. That Onza looks nice.
Of course, a wheel and pedal setup is going to easily be the most fun. But a good setup will run quite a bit more than a controller. And for some games, especially arcadey racers, a controller is going to be faster and easier usually.
BTW, you don't need the PC version of the 360 controller. It's like $5 more and identical to the regular ones except it comes with the software, but you can download that anyway.