Some people on this board will flame me for wanting to consider a “commie gun,” but an AK doesn’t seem like too bad of an idea because of the take-down power, ruggedness, and the fact that they are dirt cheap. Of course, accuracy is shite.
To each his own. Get what you are most comfortable with.
Anyone who will flame you for wanting an AK variant is an idiot. Even the cheapest WASR converted to 30 round mag AK is going to be pretty much rock solid reliable and be able to hit MOM, Minute of Man, at any reasonable range. That is, if you can hit, it can.
Ammo is still fairly cheap compared to .223 or .308, and within a couple hundred yards they are adequate.
For a real value, seek ones with chrome lined barrels and chambers, they are less susceptible to pitting from corrosive ammo.
It takes about ten minutes of instruction to have someone be able to use one, speed at reloading and skill come with practice.
If you want pinpoint accuracy, you are not likely to get it with the AK or SKS, but sub-MOA accuracy is a sniper's tool for ranges beyond the AK and SKS anyway. (A neighbor just starting won't be able to take advantage of a better rifle).
If you want that standoff capability, it takes a better knowledge of ballistics to use effectively and some fieldcraft--things you are not going to be able to impart to a neighbor in 10-15 minutes--and it will cost more for ammo and the arm and the optics.
Most rifles that accurate and set up for long distance applications suck as a CQB weapon, anyway.
While the AR 15 (or other Stoner variant) is a good tradeoff between the two, that is for when you are only packing one, and unless you have the piston upper, the AR will be more maintennance intensive.
(Keep 'em all clean, but some need more TLC than others.)
For the neighbors and volume of fire in a pinch, consider having a couple cheaper east-bloc arms (and plenty of ammo) around.