Mossberg 500.
Nothing says you’ve entered the wrong house like the sound a pump shotgun being jacked. (Except maybe a slightly worn slide on a 1911).
If I had only one gun a 10/22 would be high the list but the question had do do with inexpensive home defense.
Nothing gives away your position like a shotgun being racked, too. Sometimes a good semi-auto shotgun is worth it.