I've been using fish as my default shell for ~3 years now. The faint gray history auto-complete / search that appears when typing commands alone is a killer feature. urxvt + fish + ranger + sauce code pro font = me loving my terminal experience a ton. Thanks fish devs!
If anyone here is a zsh user and interested to use the same feature: https://github.com/zsh-users/zsh-autosuggestions It really was a game changer for me as well.