i3 is my #1 reason for wanting to switch from MacOS to Linux. I love a good tiling window manager, and the workarounds to emulate a tiling WM in MacOS just aren’t close enough to the real thing.
Do not wait and get a Linux system with i3 tomorrow. You will be so much faster and more structured in your daily workflow than with Alt-Tab.
A nice side effect: Apps feel much faster than on OSX. I don't know why but everything is snappier and just more resonsive despite a much weaker CPU and same hires screen on the Linux system. Especially the terminal rendering and application switching which is instant.
Not trying to start a flame war but once I managed to install it how I liked the entire system felt so cohesive and well designed. (Ifconfig handling wpa for instance) and it turned out to be so much lighter that my laptops battery life went up 20%.
It was an older thinkpad though. So I guess YMMV.
As a long time awesomeWM (and other tiling WM) user, I've found it to be more than acceptable.