1. Fully automatic weapons are illegal in the United States without a permit, and even then, are legal only if maintained at specifically licensed clubs and ranges. You can't take one home with you.
2. There's no great virtue in fully automatic fire except at essentially point blank range against massed targets. Outside of that context, it's just a way to blow through ammunition more inefficiently.
3. For most civilian purposes, I think you'd be better off with a bolt action hunting rifle fitted with good optics. Much better accuracy, much better range, and far better "stopping power" than assault rifles firing carbine cartridges.
4. If you feel you need a military style rifle (i.e. semi-auto and higher capacity magazines), I would recommend an SKS over either the Kalashnikov or AR-15/M-16 variants. The SKS fires the same relatively cheap, widely available cartridge as the AK-47, has the same rugged, nearly indestructible construction, is slightly more accurate at range than the Kalashnikov, and costs roughly half as much. The "downside" to the SKS is it has only a 10-round magazine, as compared to the 30-round magazine standard with the AK-47 (and, the SKS doesn't really have the capacity to be converted to full auto fire, but whatever - that's totally unnecessary anyway). However, if you keep your extra rounds loaded on stripper clips, the practical rate of fire for both weapons becomes virtually identical.
5. If you're thinking about a handgun, you want something that fits comfortably in your hand and has recoil you can handle even if you aren't in a perfect stance. For most people, that means something other than the 1911, which is unquestionably a great pistol, but is more of a monster than is practical for the average person. The other really important consideration is the availability of ammo for your pistol. For this reason, I'd look at guns chambered for 9mm or .40 S&W, which are rounds with adequate stopping power that are also easy to find and relatively affordable. .380 is also an excellent round, but, because it is a popular round that isn't used by many law enforcement agencies, it can be hard to find. 9mm and .40 are the most common law enforcement calibers, so they're produced in much greater numbers and are more easily found. Plus, you can take them off the bodies of Dead Feds.