I found the Microsoft Word program on PC the best word processor by far.
I haven't tested the online version of Microsoft Office yet, but I expect it to be a lot more functional, and bug-free, than their Android app.
I suspect you've probably heard of LibreOffice, or even Google Docs, as possible alternatives.
If not, you could give them a try, LibreOffice is open source, so it's possibly safer than the proprietary Microsoft Office, and is compatible with Microsoft Office files.