Firefox 57's sweeping changes ruined most of my vim-like ui customizations (vimperator, vimfx). For 2 months I've switched to qutebrowser and palemoon as a backup and dont miss firefox at all.

If you're looking for a browser with first-class vim compatibility qutebrowser is outstanding.

I've also found palemoon to be a perfectly boring/stable/functional variant of firefox without all the drastic/breaking changes (vim plugins work quite well also)