Choice of writing tools is fascinating to me. I’ve been touch typing since I was a kid (it was the only way I could convince my da to give me a typewriter), but the first full-length book I wrote was in byro on yellow A4 pads. I had started it on a Selectric, but after a few days I loathed the incessant, demanding hum of the motor, and the irresistible urge to type as fast as I could (which is rather fast). It was a deep nonfiction book, and demanded thoughtful, precise language. Going slowly changed my entire mental process, and brought out depths of insight that would never have had a chance to develop while racing through it on the Selectric.
Since then, I’ve used dozens of editors – I used to co-own a company that converted documents among the various first-gen hardware “word processing” machines (PDP-8, Lexitron, Vydec, Xerox) and the first computer editors (vi, EMACS, WordStar). Many of those early systems, soft or hard, were quite good. When the PC’s took over, and Word ended up with the lion’s share, I began searching again (I have disliked Word since its first MSDOS versions) and I’m now using InDesign, NoteTab, UltraEdit, Scrivener, and of course now Atomic Scribbler. Each has its advantages for many kinds of writing (UltraEdit is used mainly for computer text (HTML, XML, programming, etc.) But like you, I prefer something simple and direct for tablet or phone use. Most of the time my mobile devices are on wifi, so I’m very happy with Google Docs. I don’t have immediate concerns about security, but if I were working on something sensitive I would certainly avoid the cloud, and stick to my airgapped old PC with whatever editor fits the task.
For fiction, my current workflow starts in AS, or perhaps originated in Scrivener and stays there, and then – because I’m addicted to a published-looking presentation (and I’m also a book designer and graphic artist) – it moves to InDesign when I think it’s “done”. This means that I do a lot of editing, polishing, and composing inside InDesign, because it’s never “done”!