SovereignCopper MixPlorer
Still the most feature rich and customizable file manager available, especially when it comes to networking
I just recently replaced it by Material Files that even has proper WebDAV- and multi-window-support.
Unfortunately no direct cloud support. But I've read there are third party solutions to bridge Drive to WebDAV 🤷
Speaking of Clouds: If that counts as "feature", when not relying on my own server I'm a user of Infomaniak's Kdrive that I can connect to via WebDAV and therefore mount it to my phone directly.