Bend the knee. Apple has won for now. 

If you are not a geek, as of years ago, you have only one somewhat safe choice. It would be better if Apple hadn’t screwed backups, but your best choice is current iOS. On Apple hardware of course. 

In a year maybe Windows S on Microsoft hardware. Eventually Android “S” on Google hardware, but Google missed the boat. Arrogance I suppose. 

Chromebook – if Google backpedals on Chrome/Android integration. 

Dangerous is macOS run as non-admin on, of course, Apple hardware. One version behind is fine. 

Very dangerous Windows 10 with constant updates. 

Insane the rest.

Eventually devices will deactivate when their OS is unsupported.