I used WPS before, and switched to onlyoffice, because WPS had a lot of annoying pop-ups, too many formatting glitches and I liked onlyoffice’s UI more.
There’s just this BOOKMARKING feature on PDFs that I found really useful and is missing in onlyoffice.
I could set bookmarks for every page, and organise them in a hierarchical structure, meaning I could have say a bookmark for “Chapter III” at page 63, and under it, I could set bookmarks for subheadings at 68, 72, 79, or whatever pages, that I could subordinate to the chapter bookmark, in a dropdown menu.
You could move the bookmarks as you wish in the bookmark panel, with a simple drag and drop gesture, edit them, change their colours, etc. Very useful!!! Especially in large documents.