Not an i3 user, but xmonad should be close enough. I'm using termite nowadays. It's configured by editing a plain text file in your editor of choice (as opposed to a GUI), it does not have buttons that take away space, and the vim-like visual mode is a game changer for me. The only annoying thing is that it sets TERM=xterm-termite, which machines you log in via ssh usually don't recognize because termite is not installed there. Easily fixed in your .bashrc.