I start with paper and progress to the laptop. Luckily, my writing files show on my phone, so I can continue the story if the PC is occupied by someone else.
My ideas flow best on paper.
My writing is better when I write it with pen on paper, but I prefer a laptop because it's easier. I type faster than I write, and there aren't those pesky erased lines and you have spell check! Plus, typing it up after you've written it on paper is just a pain.