I mostly use C-x C-m instead of M-x as I for some reason find it less
annoying to type. I really like helm-command's helm-M-x function, but I
find slightly too slow and slightly too intrusive than smex.
Hence I'm switching back my main keybinding to smex, but still leaving
helm-M-x bound to the M-x keybinding I use very rarely, just so I can
still access it when I need to.