Having owned almost all the main NR Black Rifle options, the ones that are worth it in my opinion for:
●.223/5.56:
-Tavor if you like short and light handling
-ACR if you like accuracy, caliber conversions, and conventional ergonomics. Build your own caliber conversions, if it will feed from a Stanag Mag, the ACR can handle it. 5.56-.50Beo.
-Modern Varmint if you like the AR platform and are stuck on the ergos it provides. Also carries accuracy potential similar to the ACR but is yet to be tested as none are in owners hands just yet, however it looks promising.
●7.62x39:
-VZ58 for a cheaper entry level rifle that feeds on cheap surplus.
-XCR-L if you feel the need to subject a $2500 platform to corrosive ammo and use mags that dont feed 7.62x39 reliably in larger normal sized mags. Has conversion kits readily available, 5.56-7.62x39, but lacks accuracy potential in my experience. Good plinker, but mine got replaced by my ACR.
●7.62x51/.308:
-M305 for a cheap surplus eater that has DMR potential with enough money and tweaking.
-RFB if you want a compact thick bush rifle, good accuracy potential, especially if you are a hand loader from what I have seen.
-High end M14 (M1A/LRB) DMR accurate out of the box, this design is tried and true.
-Modern Hunter beats them all, but bring your piggy bank. Resembling the AR10, this platform borrows alot of the features that make the AR10 great. As the big brother to the Modern Varminter, it has displayed lots of potential.
These are the platforms you should consider in my opinion, everything else will leave you wanting to upgrade. These platforms should leave you satisfied as long as you know what they are about going into them.
Just to add my experience, as I have also owned a bunch of these rifles:
●.223/5.56:
-Tavor - still have it, and it is boringly reliable. It just works. Optics mounting is a breeze. It has built in back up irons. I'm sure it could slice and dice too if I asked it to.
-T97 - Cool rifle, but not 100% reliable in my experience. I never broke any parts, but periodically it would fail to feed, and the magwell doesn't seem to work great with all mags. Hard to mount optics on unless you switch the upper. I would maybe own another one. Its kind of old school like the SG540 in a way.
-VZ58 - rifle totally self destructed (locking lugs in the receiver deformed, and the headspace became unhealthy) - fell apart at about 1200 rounds IIRC. I also broke a firing pin on it before that. Proprietary mags (i had the gen1 ar15 mag adapter, but it wasn't very good - ftf frequently - jam the projectile into the case).
-XCR (keymod) - decent rifle. once in awhile it would also fail to feed, but ran better than my vz58 in 5.56. Never broke any parts, but keep an eye on the threaded components. My gas block was loose after the first 100 rounds or so.
-SG540- reliable, but I only had it for 100 rounds. Cool gun, but the ergos and furniture are too old school for me. Soft recoil. Expensive accessories.
●7.62x39:
-VZ58 - great rifle (the platform is super fun to shoot - mags are flawless too), bolt cracked at 1000 rounds, got it fixed on warranty, and sold it immediately with full disclosure. No great options (in my opinion) for optics mounting. I would own another. Got this rifle on warranty exchange for my 5.56 vz58. Left a bad taste in my mouth for that manufacturer...
-SKS - have one, still have it, it still just works too. The trigger sucks, but the gun runs.
●7.62x51/.308:
-M305 - I've had two, and they are heavy. optics mounting isn't great (I had one in a blackfeather stock as well). Cool gun, but too old school for me.
Summary - I'm a big Tavor fan. I just don't think (and this is just my opinion) that rifles designed for civilian markets such as the XCR are going to have the same level of field testing and reliability that the Tavor has. The gun just
runs. The feeding and magazine well have been refined to work extremely well (for me anyway). First 5.56 rifle I can say that has been flawless for me. No broken parts, malfunctions etc. Great rifle. Right now I can't see anything out there that would replace it for the type of shooting I do (unless the AR15 became non restricted). I would add an X95 to the stable to keep it company.
Feel free to shoot me a PM if you want to hear more about any of these rifles.
Someone asked earlier about why the MR1 is not popular - for me it is the shotgun-esque ergonomics that totally turn me off of it. I love the ergonomics of AR15's and bullpups. Weird, but that's why I wouldn't buy one. I also like guns that use the same optic height as AR15's, as then I can swap optics between rifles more easily if I feel like it.
Ben