It depends on what features you need. Libre Office is a suite with database, word processor, spreadsheet, Abiword is just a word processor, WordGrinder is terminal based program specifically for first drafts that can export to ODT, HTML, etc., O20.Word is a clone of MS Word 2019, there are more: Calligrawords, Focuswriter, etc.

Abiword is probably the best compromise between simplicity, familiarity, and features. It's also very lightweight.

You should also consider Emacs Org-mode.