Switched to i3 a few weeks back and I absolutely love it. Switching between applications and workspaces is incredibly fast, and the _only_ time I need the mouse is for web browsing. It's amazing.
Unfortunately it appears all of the most popular (and feature-complete) Vim-style plugins for Firefox are dying with the upcoming Firefox update dropping support for XPCOM/XUL plugins.
Unfortunately, it'll also be obsolete in a few weeks when Firefox 57 comes. I've switched to Saka Key, but it's not yet a viable replacement (esp. because clipboard interactions are broken in FF 56 on my Linux systems).