I would go with OnlyOffice, I’ve used it before and it seems to handle MS Office files a bit nicer than LibreOffice. I personally use LibreOffice, but it does sometimes burn me when an formatting issue pops up (worst example was a presentation where I set a partially transparent background image which MS somehow interpreted as making all the images transparent, ruining the legibility of the images!)

Someone has already suggested MS Office for web, but that a) requires a stable online connection and b) the web apps by Microsoft are, in a few words, complete ass. Everything loads ridiculously slowly, and formatting is inconsistent in my experience (think stuff like line spacing, font sizes). I really dislike editing on Word on Web, and in my old school, we used Microsoft Teams which just chugs and takes a good while to load anything. Why Microsoft can’t figure out how to make a decently performing web app I have no idea.