LibreOffice, as I've been using it from soon after it was forked from OpenOffice and I'm used to it, and I don't think it's worth it to learn how to use another office suite when the one I use works fine for everything I need to do. I had tried OnlyOffice on another computer and I was positively impressed, but not quite enough to feel I should switch; in the end I only even use a small subset of the features LO has.