My experience is that I can drive smoother and cleaner with a wheel but I can react faster with a controller.
The biggest advantage I find to using a wheel is that I can brake far more effectively and consistently. I do struggle sometimes to hit the perfect braking force with my controller but with the steering wheel and pedal set up I can hit it every time.
The biggest advantage I find to using my controller is that I can relax and put my feet up. Sometimes I’m just not in the mood for sitting in a rig with my arms and feet perched on the wheel and pedals. More often than not I want to sit back, stick my feet up and just twiddle my thumbs.