OnlyOffice is indeed a good choice for the best MS compatibility. Also Google Docs is amazing for collaboration in teams (yes, I know it’s not FOSS, but hey, it works). NextCloud is nice but it doesn’t offer collaborative editing of Office documents AFAIK.
For presentations I have been lately preferring Inkscape. It has multi-page support since some versions ago and can export to PDF, clickable links and everything. I don’t use animations or anything too fancy in my presentation and I like the flexibility that a vector editor can offer me, so Inkscape works well for my case.