When it comes to writing, I think it’s like exercising: whatever is most comfortable for you to use, and stick to writing with, that’s probably what you should do. Writing takes enough concentration out of the brain as it is. You don’t need to be fighting the distraction of the wrong font size or sparkle-pink ink on top of that.
Like anyone’s personal toolkit, mine is a bit idiosyncratic. For one, I prefer Bic Crystal pens – I can grip them very hard, and yet they won’t bend or wobble. When your mind’s caught up in a thrilling action scene, this is important. I also tend to scribble down stray ideas and rough drafts on scrap paper, just to get past the mental hump of “maybe this isn’t a good idea after all”. Then I type it up in Word, where I can shuffle all the scraps around, reword bits, and do bits of a very rough first edit as I pull it together.
…Most of the time. There are times my brain is being particularly sulky. Or when even a half-sheet of scrap paper seems like too much empty space to face. In that case, what sometimes works is pulling out the notepaper I ran across some years back, the stuff that’s made from sugarcane. It’s a bright paper, with a satin-smooth feel to it, nice on the hands; skin contact can help lure the brain into writing something.
(Not the cheapest paper, but I got a multipack of the small notepads a few years back and haven’t used them up yet. Usually a sheet or two is enough to get the writing gears going. Or suffices to hold what little I can get until I have energy to write more later.)
Don’t neglect the little physical aspects when you’re typing, either. Technology may allow files to transfer from phone to internet to desktop to whatever, but your physical reactions aren’t as fluid. You’re trying to get the words down without thinking about them as you write; a different spacing on the keyboard than you’re used to, different keys to hit, will slow down what you’re doing. And if you have to think too much, you may lose the writing thread.
Writing is a craft. Like any other craft – beading, carpentry, what have you – you must pay attention to your tools. Find what works for you!