Keyboard all the way for me. It's way faster than writing by hand and also I can easily edit what I've written. Though I need a proper keyboard for that - the best one I've ever got is an ergonomic one. It was really strange at first, but I quickly got used to it. I generally type fast, but I was able to do it even quicker using this keyboard. Too bad they discontinued the series where I live...
Now I have laptop, but it's still good enough - the best way to write something for me. Tablets and smartphones are a big no for me - I need a big, physical keyboard to be able to type properly. Though there are times when I write something by hand - usually when I have to draw something or type some numerical formula. That's also the reason why I always carried my notebooks to classes, when I still had one - it'd be impossible to write down something else than just the plain text.