While I’m a big fan of Vim, it’s definitely not for everyone.
I spend about half of my writing time in VSCodium, which is a community-based release of Microsoft’s open source VS Code editor. There are several markdown, grammar, and focus-oriented plugins for the platform, and you can pretty much shape it into whatever kind of editor you want.
I use VSCodium for the vast majority of my personal notes, technical writing, and project documentation (nearly all of which are written in markdown format).