In my experience owning both brands ( Pa3x and Psr s900) and having them integrated to play simultaneously I can say I keep swaying from one to the other. There are times I play basically the Korg styles and others the Yamaha's. But I play the psr styles with the Korg drums what makes the big difference. Choosing the best sounding board is only a part of the realism you can get. Yamaha leads on SA voices and smoother chord transitions. Korg leads far ahead on drums and modern styles.
Sometimes I think my ears get bored from one board's sounds and need a change, later I miss the former.