I thnk that a decent case can be made for the fact that, for non hunting purposes, the AR-15/M-16 should really be considered America's Rifle.
The number of manufacturers turning out AR framed designs seems to grow every week. Of course Colt, frustrated or in retribution for the Mass. AG regs that basically prohibit the importation of Colt pistols into the state, does not ship to Mass. and Kimber of America, also a manufacturer of hi quality 1911 framed pistols has taken the same position.
Personally I have 2 Colts, (1 the HB variant) an Armalite (formerly of Costa Mesa CA. and also formerly makers of the Ar-18.)a Bushmaster and a Smith & Wesson.
I have another "black rifle" or two, one by SIG and One by Ruger based on different actions.
This accounts for 4 manufacturers alone
The Ruger M-14 is an M-1 style turnbolt action. Its gas system is less (much less) likely to inject any dirt into the firing chamber area. Expanding firing gases are, as in the case of the M-1 and M-1A, taken downwards to impinge on a very short operating rod which works the action. I am embarrassed to say that I have not spent much time with the SIG, so I cannot really state with exactitude how the gas system i constructed except to say that it is a "piston" based action instead of the "direct impingement" system of the Colt (Stoner) design.
This Ruger is simply a slightly modified Mini 14 with a recoil compensator, fiber stock and , of course, black finish.
Despite a 13 year ban on the importation or manufacture of over 10 round mags for semi autos in our beloved Bay State, hi cap mags are readily available for the AR and Mini 14. Leading to the conclusion that somebody must have made or bought a very large quantity of these mags before 1998.
Ruger has now introduced their SR-556, which is, at least, 'styled' ergonomically like an AR 15, but I have not handled any of these new items.
FN is now importing an ergonomically similar rifle to the AR, but I hope it is based on the "FAL" or "FNC" type of gas sytem.
Other manufacturers include DSA, Olympic Arms (Washington State

It should be noted that there is a recall notice out on the "Bushmaster ACR" interchangeable configuration AR. My Bushmaster is the Fluted HB type and offers excellent accuracy. We shall see how the Armalite does.
The basic attraction to the rifle is the price and availability of 5.56mm ammo. I am in total argreement that the proposed 6.8mm SPC Cartridge is a better fir for the military, but for us, the cost of a box of 20 rounds would probably be in the $1.00 a round category-or about 2-4 time the cost of the 5.56mm, which has begun slowly to climb in price to the extent that Hornady will be offering "Steel Case" ammunition which, like Wolf, will offer a considerable savings to the non reloading shooter. But with 4-5000 5.56 Hulls lying arounf ready to reload, I am not going to make any changes.
Since the new location of Armalite, to jump back a step, is Geneseo Illinois I might hazard a bet to the effect that Springfield Armory purchased that company name, at least.
As to the Rifles immediate predecessor the M-14. it seems to be the obsolete rifle that will not die.
Militarily it has range and power well exceeding the AR and should, perhaps, be put in the hands of the designated marksman of an infantry squad. It is still in use as a Sniper Rifle and in a "Rifleman's War" in Afghanistan its power and range would get my attention.
Ie: if someone is shooting at you with a Dragunov, you are going to wish you had an M-14 derivative around as the M-4 or M-16 would be out of their depths in dealing with that weapon in the hand of a seasoned sniper or even the above average shot!!
I am Going to sigh off for now. If you can think of more manufacturers of the AR frame, do let me know.
also my comments about the M-16 Clan (as much as I like the ergonomics) are going to be far from positive given the tactical realities of Afghanistan.
J