There is one showstopper, why I can't recommend Firefox to friends:

Mozilla's refusal to support the File System Access API.

With the File System Access API, we can finally build local first web applications.

I already wrote my own todo-list app and text editor and some other more specialized apps that work nicely in Chrome (On desktop and mobile). And I am in the process of writing a photo gallery too.

One can build workarounds for Firefox with old-fashioned download and upload buttons, but the user experience is miserable. Directory based tools like a photo gallery (for local photos) are not possible at all.

With the File System Access API, web apps feel just like local productivity apps.