What do you use to write/share/search/organize engineering docs?

Our team has tried Google Docs, Notion, Dropbox Paper, Coda, and now we're looking at Slab. All I want is a single place for people to write things down where we can all find those things afterwards. They all have inadequacies. Here is the feature list I want:

- Searching across all docs in the project works quickly and accurately, and shows the matched phrases/parts so you can determine if it's actually relevant

- Easy tree structure organization of all docs, without arbitrary distinction between top level and sub-level pages

- Editing interface that lets you write collaboratively and looks decent. Should work like a regular text document.

From my testing, here's where they each fall short:

Google docs: best at editing/writing. No tree-structure organization without using Drive. Search is ok.

Notion: best at organizing. Editor is laggy and absolute garbage. Can't select half of two paragraphs, you'll end up block selecting. Organization is still weird, some subpages are visible in the side bar some aren't.

Coda: best at editing/writing, but not perfect. Searching is ok. Tree-structure is inadequate, weird division between pages and subpages.

Paper: best at editing/writing. Search is bad. Organization is bad without using the rest of Dropbox.

Slab: haven't evaluated yet.

I am this close to throwing my computer out the window, or burning all of my goodwill points and picking a solution at random and forcing us to use that. Please help.