Which would you grab?

Are you insane? If you aren't going to use the gun then you should have bought a baseball bat. You shoot them in the knee then call the police.

It's more psychologically scarring to see someone charge at you swinging a shotgun like an absolute madman

The intruder might turn the gun against you, that freaks me out.

Same. I couldnt shoot anyone. Same with a knife. Me holding a knife would turn into them talking it from me because I couldnt bring myself to stab them.

I'd probably call the police and try to get out. If it came to it, I could hit them over the head but I'd probably panic.