The reason the AR-10 doesn't really interest me is the cost involved. For instance, one can find a Mosin Nagant for $200, easy. AR-10's would cost 5x that at LEAST.
The longer cases interest the the most, in the family of .30-'06.
The FN-FAL gave the guys fits on Top Shot. Is that indicative of the platform?
What does the M-14 fire, since that's a popular one so far?
And the AR-10 is 5X the rifle the MN is. Considering the WWI/ WWII surplus relic in the same conversation with a moden battle rifle is frankly, silly.
If longer cases are more "intersting" to you then get a Garand or FN-49. The Swedish Ljungman/Hakim may interest you.
If you are going to base your acquisition on a TV show, we have a problem. Why not a Winchester 1982 because Chuck Conners carried one in "The Rifleman"
"What does the M-14 fire"? Really? I do not know how to take this. The M-14 rifle fires the 7.62 X 51 (NATO) cartridge. It will also accept the .308 Winchester commercial cartridge. No, you cannot have an M-14 (unless you have a VERY stupidly large sum of money laying around. The M-14 is a selective fire rifle (machine gun) and there are very few transferrable specimens out there. They bring a premium even in comparision to other machine guns. IF you can find someone willing to part with one, it woud likely set you back $20,000 or more. Yes, I said 20K!
WTS there are a number of M-14 clones out there. The Springfield M1A being the most notable. The Chinese made Polytech's up to the Smith Enterprises versions can be had for far less. ALL of these are semi-auto and should not be considered M-14's anymore than an AR-15 is considered an M-16. (don't get into the fact that the VERY early AR-15's made before they were accepted into military service were in fact select fire machineguns.)
Onward;
The 7.62 Nato rifles available are (certainly not a complete list)
M1A and its various versions
HK-91 from Germany or may other iterations
CETME (kind a a Spanish HK, but not really)
FN-FAL and others based on this design
AR-10 (itself a slect-fire machinegun from Armalite and other rifles made semi auto by various makers)
Keltec RFB (a bull pup configured rifle that is new to the market)
I have an HK-91 and a CETME. They are great guns, but shooting commercial .308 ammo is not advised because of a design feature that makes it a bit iffy. Plus side? VERY cheap magazines available,$2-$5. No gas system to foul as it is a unique delayed blowback operation.
I am considering an AR-10 in the form of a Rock River LAR-8.
The Keltec offering is interesting, but IMHO unproven.
The M1A is the standard by which all are judged. Not perfect, but available in a wide variety of trims from basic, synthetic stocked rifle to super accurate National Match and sniper grade rifles that are capable of accuracy on par with some of the best bolt action rifles. Down side? Good magazines are pricey.
FN. Well, the FN-FAL and its various iteraions made by England, Canada, Australia and Belgium (and a few others) are considered the shoulder arm of the free world. There have been more examples of this rifle made and distributed throughout the world than any other battle rifle in history. The AK-47 (an assault rifle) is/was made in greater numbers by the "enemy", but the FN has seen action on nearly every continent. The magazines are plentiful and relatively cheap (make sure you get the right kind as there are "inch pattern and metric" magazines.