The writing medium I use — keyboard or paper — depends on my mood.
Many times, I prefer to write on a keyboard. It's faster, more convenient and I get a better idea of how long my work is (word count feature!). I'm an espeically fast typist. I can type at 79 words per minute, so I can rip through the keyboard in no time.
But when I'm experiencing tough writer's block at my computer, I use paper. It helps with my writing. It's because I've reached my creative point at the keyboard and I need a change in my system. When I'm editing my books and I don't know what to type anymore, I print out the hard copy. Then I take my red pen, edit, and transcribe the changes to my laptop. When I write new poems, I find that it's more helpful to write on paper than the computer. Then I type the verses on the computer, and continue working on there.