The M-14. It's accurate, reliable, has an ambidextrious safety and magazine release, doesn't chuck brass into the next state, can be had with a regular stock (synthetic or wood) or pistol grip E2 or folding stock for those that prefer something more compact. Contrary to what Mad Dog claims about ALL scope mounts form the M-14, the Brookfield Precision Tool scope mount does NOT suck in the very least. I ought to know since I have one on my M-25 clone and have no problems with it at all. It's also a versatile weapon being able to be set up as a regular rack grade rifle, match grade rifles, long range sniping rifles, compact bush rifles with the folding stocks are VERY compact and also "sexy" with the BM-59 style folder, or can be set up in the E2 version if you want to dump a lot of rounds on target fairly quickly.
The M-14 also has the best sights for the rifleman and a decent trigger to go with it. Even a rack grade trigger is better than either my FALs or HK91. Another thing to consider is that in the post-ban world, the M-14 can keep it's flash suppressor instead of having to have a loud, flash-enhancing muzzle brake found on post-ban FALs and HK clones. Sure, the magazines can cost around $25-$31 depending on weather you are looking at Chinese or USGI magazines but they are VERY well built and not as likely to get damaged as lighter weight magazines. I tend to look at mine as an investment in quality. No, the days of $5 and $10 USGI mags are probably gone but cheap FAL magazines are only one penstroke away from not bieng allowed to be imported anymore either.
My FAL comes in second loosing out to the M-14 in the area of a heavy trigger, crude sights, and on the metric rifles, a safety lever that is too small to manipulate without shifting your grip. The inch rifles are better in this area but that folding rear sight always seems to fold down at the worst possible times.
The adjustable gas regulator is a nice touch but then again, I haven't had any problems with my other rifles that don't have this feature either. The cheap magazines of the FAL are a good selling point though as long as you are looking at metric magazines. The inch magazines run a little higher but like the M-14 magazines, I think they are a little more rugged. Of course, cheap magazines are around only as long as the powers that be will allow them to come into the country.
Again, the flash suppressors (both the long L1A1 and G-series flash suppressors are pretty good but the shorter "combination flash suppressor, grenade launch" type isn't that good) but with a cheaper post-ban rifle, it's no flash suppression for you!
My HK-91 is my least favorite mainly because while it's accurate and reliable, that's it's only saving graces.
The handguards heat up too fast, there is no bolt hold open device, I find the charging handle awkward to use, the magazine release is too far forward, the sights need a special tool to adjust, the trigger is WAY too heavy, the safety can't be manipulated without shifting your grip, ejected brass is seldom found so I wouldn't say the HK is "reloader friendly", the stock is too short for American style shooting, the recoil is sharper, putting the bolt head back on the carrier after cleaning is a real chore and cleaning the breech face and chamber area is hard to get at as well. Did I miss anything?
Like I said, yes, it is reliable and yes, they are accurate but after that, their design really falls apart in the handeling chacteristics and not so much the dissasembly but the reassembly of them after taking them apart.