My vote would be for a pump action 12ga first (preferably with changeable barrels if those exist in the market), semi after that.
(+) Pump action shotguns are relatively cheap
(+) They are reliable as hell vs semis
(+) The sound of reloading pump action is one of the most intimidating sounds in the universe, on par probably only with AK action sound
(+) If you practice enough, you can get very fast operating a pump action
(-) It has more recoil than a semi