The top competitors of the Aprilia RS 660 include the BMW S 1000 XR, Honda CBR1000RR-R Fireblade SP, Kawasaki Ninja 1000SX, and Suzuki GSX-S1000F. Each of these models offers a similar level of performance, with the BMW and Honda being the closest in terms of power and the Suzuki and Kawasaki being a bit more affordable. The Aprilia RS 660 stands out with its advanced electronics package, which includes a six-axis IMU and three levels of traction control. It also has a slightly larger engine than the other models, and its light weight makes it great for tight turns.