You can try either Tridactyl[1] or Vim-Vixen[2]. They come pretty close to the Vimperator experience (although with WebExtension limitations).

I'd recommend Tridactyl with native extension though (install the extension and type :installnative), as they've done a really great job re-implementing Vimperator features using a wrapper Python script (e.g. support for .tridactylrc, modifying UI[3], open with external editors, etc.)

[1]: https://github.com/cmcaine/tridactyl (use the beta)

[2]: https://addons.mozilla.org/en-US/firefox/addon/vim-vixen/

[3]: https://imgur.com/7vQANhV here's `guiset gui none` with buffer list open

Thanks for the tip-offs! I too have been stranded without a decent vimperator replacement for a while. Currently using Saka-Keys but not in love with it, so I'll experiment with these.

Try https://addons.mozilla.org/en-US/firefox/addon/vimium-ff/.

I've used it for close to a year and it's decent. It has some issues like all the other Vim plugins, but it works well enough.

QuteBrowser?