For scientific writing, you've also got https://manubot.org/ which combines git (for versioning and collaboration) and markdown and multiple good-looking outputs

One of the most useful features is that you can just insert a doi/pubmedid/... and it will automatically fetch and format the references

Edit: One of the biggest problems with the tools for scientific writing is that the writing process if often a collaboration - one author makes a draft, distributes it, and receives comments and revisions. Currently - and sadly - I think Microsoft Word has the best solutions for commenting and revising text, although you have to keep track of multiple versions being emailed around

Edit 2: "We will use our servers to create PDF files" is a no-go for certain documents - unpublished papers are often regarded as quite sensitive