Backtick is my favorite too. Interestingly I thought it was an obscure choice, but it seems to be the 3rd most popular prefix from an analysis of tmux.conf fil

Backtick is my favorite too. Interestingly I thought it was an obscure choice, but it seems to be the 3rd most popular prefix from an analysis of tmux.conf files on github (after Ctrl+A and Ctrl+Space). I use `` (double-backtick) to escape the backtick and it's eminently reasonable.