I use slow. You can use whatever feels better or is comfortable for you but personally on Slow I feel like it's more of a challenge to run the ball for myself and the coverage is tighter, which I like hard fought defense games. On normal the speed of your decisions have to be quicker. You need faster reactions but I find it easier for myself to run the ball and my WRs get a little too much separation more often than I like. Not to mention I do enjoy the animations and smoothness of Slow. Both game speeds play well.