How to change the Windows ALT+TAB hotkey to something else?

If you use Windows 10 version 1903 or higher, you can use PowerToys by Microsoft for this task. Its user interface is simple. It has a lot of functionalities, one of which is it allows us to remap keys and shortcuts to other keys/shortcuts.

You can download the installer from release page > "Latest Release" > Scroll to Assests > download PowerToysSetup EXE file

I switched from Mac to Windows and missed how comfortable it was to use Command key for both, to switch between apps and for other shortcuts(Undo/Copy/Paste :D). Now my thumb rests on the Alt key(remapped to Ctrl) and I can perform all shortcuts easily. I used this tool to remap my keyboard shortcuts. Here's a screenshot of my settings:

You can use AutoHotkey for this purpose:
https://www.autohotkey.com/docs/Hotkeys.htm#AltTabDetail

Please note that Ctrl-Tab is interpreted by many programs to change tabs or Application-internal windows. These programs won't receive the key presses anymore if you follow the steps below.

AutoHotkey is a script interpreter, therefore you need to

1. Install AutoHotkey
2. Write your own script file (.ahk extension). In your case it just needs to contain one line:
   LControl & Tab::AltTab
   It tells AutoHotkey that you want to hold down left-control then press tab.
3. Start your own script. It will show up as a small green icon at the lower left corner and wait for you to press keys.
4. Optionally start your script at every Windows reboot. One way to do this is the Autostart folder. Press Windows + R and run this: shell:startup. In the folder window, place a shortcut to your script file from step 2.