My roommate used to work at RnRC when I was on the program and he was telling me it was either the 5-7th seat that has the most force put on the car due to the fact that is the car where the driving force is put on the car.
I enjoy the back seat in most coasters, especially in RnR because you get pulled through the ride and never experience braking in the loops or that last hump you go over before the exit.