I prefer using Adobe Lightroom to catalog my photographs. At one time, I had to close Apple Photos every time I inserted my memory card. Now, I only need to Import my photos using Adobe Lightroom.
You may have tried to uncheck the Open Photos checkbox, but this is reset every time you format your memory card.
To disable or stop Apple Photos opening when you insert a memory card simply open Terminal (shortcut: cmd+space and type - terminal) and enter the following command:
defaults -currentHost write com.apple.ImageCapture disableHotPlug -bool YES
If you ever want to re-enable or start Apple Photos opening when you insert a memory card simply open Terminal (shortcut: cmd+space and type - terminal) and enter the following command:
defaults -currentHost write com.apple.ImageCapture disableHotPlug -bool NO
The only thing changed in that command was the very last word.