If you have never installed Apple's Pages application via the Mac App Store, then it is off the list of choices as you cannot get it now for Catalina.
Your choice of word processing application then distills to whether you need to share Word and PDF documents with others in a corporate setting where others may be using MS Word, or require Word documents exchanged. The free solution for that is LibreOffice which is a clone of MS Office and contains LibreOffice Writer and available Writer PDF user documentation. This is the free one directly from the Document Foundation, and there is another LibreOffice in the Mac App Store from the Document Foundation for $8.99USD that I do not install, but would provide automatic update notifications via the Mac App Store.
You can search the Mac App Store for the term word processing and there will be many applications available. Some are subscription, and others may have in-app purchases to unlock features. Others may require their own markdown syntax to form the word processing content — so do your homework to ensure you get what is right for your needs.
Then there is Softmaker that has several MS Office compatible application suites, each with a word processing application, and a different price point depending on the features you need. They have a free trial as well.