Mosin-Nagant 91/30, and Kar98k.
With or without scope depends on hnow far I expect to be shooting.
But both rifles, even sans scope, are superior to every other weapon in the game for versatility.
Easily free-aimed (at least for me), more than powerful enough, more than accurate enough, and with the bayonet ability for those close and dirty situations.
As far as house clearing, if you run into a situation where you're getting mowed down by an SMG, you made what is commonly known as a tactical screw up.