EVERYONE has their own preference of getting words down on a page. Mine will vary from time to time and depend upon what the writing is for. For instance if I am journal writing I like to use a fountain pin. My partiality is a thin nib. I have found over the years that these can be delicate. If they are slightly bent from a drop, they may still write but the flow is not as smooth. When journaling, there is no feeling quite like laying down the words like spreading soft butter across a page.
My journal goes practically everywhere with me. That is because my journal serves as a multi-functional book. It contains periodic (almost daily entries), drafts of writing (most frequently poems), notes from workshops, quotes from passages I've read, etc. When writing in my journal I like to use Private Reserve Ink - Copper Burst. Against the soft yellow ivory pages it has an almost antique appearance. But if you leaf through my journal you will find that at times there is blue or black ink and it may or may not be from a fountain pen. If it is
When I start a new journal I'm always conscious of my penmanship. I don't want any crossed out words or messy writing. That will usually last two maybe three days and then its oh hell, and just move on and write.
When I am ready to work from a draft to refine, that is when I will likely move from the Journal to my Mac Book Air. There might be a couple or more versions in the journal, but getting it to the laptop gives me a better feel for the visual aspect of the work. Visual is real important to me in poetry. I like to see how the words fill up the page or don't. White space can be as significant as ink. This also allows me to work much easier with line breaks.
I know people who exclusively write on their computer. If that works for you, by all means do it. The important thing about writing is to create as much comfort as possible. Routine writing is like exercising muscles, and just as important to a writer. You should find what is agreeable to you. That is where good writing start.