WPS Office opens and saves all files without any problems. I use it for a long time and I do not have any difficulties.I use a Linux distribution and therefore SoftMaker Office 2018, because it is compatible with Linux and better than LibreOffice.
First of all, don't expect that this product can save and read files in the MS Office format without any problems. For demanding documents, Softmaker could not always read the MS Office document ideally (e.g. text misplaced, image not in the right position). This could be problematic if you send documents to other people who use MS Office.
But I have to say that this program (and Google Drive) are already the best in reading MS Office formats, and no MS Office clone can read MS Office formats so well.
If that doesn't bother you, I think this product is the best MS Office clone.