Cochise,
I would expect you live in the country to want/need a rifle for self defense. IMO, in the country is the only place where you may need a rifle against numerous adversaries in the open. Can't do that in the city and defend your actions legally. All suburban and urban self defense should involve the phone first and a pistol or shotgun loaded so you don't kill your neighbors by firing something too powerful and too much and sending them gifts through yours and their house walls. Even if you don't like them, this is expensive and time consuming.
Now in the country one needs a companion firearm that has the power and reach to ensure that self defense can be effectively performed if the dirtbags put you under siege. However, the likelihood of this is very small, and again the phone is your first defense. Self defense is not offensive, it is indeed defense. I would probably go with a good hunting rifle in a substantial caliber. I like my Ruger Deerfield. Good to 100 yards (tough to defend legally) and a show stopper at social ranges.
If you are an NRA member and read the Armed Citizen in their monthly publication, you already know: 1] that most thugs depart at the sight of a gun in the hands of someone willing to use it. You also know: 2] They usually run like the wind at the firing of a shot, and 3] they typically depart when wounded (some, thankfully, die and cost the taxpayer no more money) to seek medical care. If you want a military type rifle, go for it. I would recommend the AR in 5.56; but, as someone already alluded to, in today's political climate, starting with an AR or other military style gun you have an uphill battle in court.
Now a lot of people say, what, a Deerfield has only 4 shots, I need more. Not so, please see 1,2,3 above. Plus, a spare Deerfield magazine gives one an additional 4 shots. Do remember, you shoot too much you also get an uphill battle in court. There are many pistol cartridge rifles that provide more shots, such as my Winchester Trapper in .44 Mag with its ten shot capacity. Marlin has some nice little lever rifles also.
Summary:
Get an AR rifle for informal target shooting, varmints and plinking. If you want a good SD rifle, take a look at one of the little semi-autos, pumps or levers offered in a decent pistol cartridge. BTW, the pistol cartridges are low in recoil and will be great to shoot for the same reasons as the AR. Practice is everything.