Best of both worlds, cheap and general purpose, get a Waffen Werks AK74 for about $600, a few commie magazines to go with it, and you can stockpile 5.45x39 surplus ammo in sealed tin for about 17 cents a round. Unless you expect to target practice a lot after things get ugly, one tin should last a very long time. (1080 rounds)
The round is cheap and effective, accurate to 200 yards and the AK is rugged and reliable in design and requiring little maintenance.
I do have an AK-74 and cans of the soviet stuff, probably 10,000 rounds.
And all sorts of other goodies, focusing on .380, .38, .40., .22LR, 5.56, 7.62, .308 and 12g shotgun galore.
But the question was, not what you have, but what, if you had limited options.