Check out Amethyst https://github.com/ianyh/Amethyst for Mac. I use i3 at home, and when I first started using OSX at work it drove me nuts until I found Amethyst.
A colleague turned me on to KWM (https://github.com/koekeishiya/kwm). If forced to use a Mac again, I'll probably use that. Amethyst never quite worked right for me, and I found myself restarting Amethyst all the time to un-break something.
Also, KWM has focus follows mouse.