SKS
It's inexpensive, rugged and reliable.
7.62x39mm is a "barrier blind" cartridge (it'll shoot through light barriers - automotive sheetmetal, automotive laminated windshield glass, cinder blocks, etc.).
You can load it with premium expanding ammo.
Plenty of inexpensive training ammo available, and you can use it in a pinch in a SHTF situation.
If equipped, remove the bayonet to reduce "swing weight", to increase agility by making it a little faster to swing the muzzle onto target and faster to stop the muzzle so you don't swing past the target.