Try this:

  (use-package window-numbering
    :ensure t
    :config
    (window-numbering-mode))

This will rebind M-1 through M-0 to become window-switching keys, and also display each window's number in the modeline. I've been using this for years now, and haven't found anything else that beats the speed of pressing M-1 through M-5 with my left hand (I rarely have more than 5 windows per frame).