I prefer keyboard. With a keyboard, i can type uberfast, and I can just start spitting out random words until they form ideas or thoughts and then these thoughts or ideas can form into lumps of thoughts or ideas that actually starts to grow into a story. I can't do that while writing on paper, because all the thoughts in my head usually dissipate by the time they get to my hand because my hand can't keep up with my mind....on a keyboard it can.