Joystick. The Korg Trinity I used to play had one, and so does my XP-80, although the Roland only goes 3 directions.
My psr and Nord have mod wheels and pitch benders as separate devices, which I dont like nearly as well. Why would I want to use 2 different devices to do some sort of expression when i could do it with 1? Ribbons are OK, the Trinity had that too, and it does have its uses, but the joystick is my preferred method.