If DPMS isn't satisfactory then perhaps a Colt? Of course, a buyer now won't be afforded the chance to own one made in the era just prior to the .Gov giving the contract to FN - because the Colt rifles weren't passing inspection and had some significant issues.
I can remember opening the shipping box of a new Government FN and it was a beaut. There was a reason Colt lost the contract - and seeing some competition for it, they fixed their mistakes and moved on.
If we have one of the few examples that seem to pop up from any makers inventory as less than perfect, be advised, that NO maker is exempt from it and they can all fail. Case in point, I have a S&W 3Gen in .45ACP that has the annoying habit of chambering empty brass if I load it in the magazine. No other gun I have will do it, all the others will jam every time and let me know it's not a viable round. Only the Smith does it.
Goes to - sometimes its not really a problem. That rail and the PEPR mount? Picatinny rails and their accessories are supposed to be compatible, but not every time. We don't know which is at fault here - blaming one and not the other without a specific cause being found isn't empirical science, it's just an emotional assessment and placing blame for it. Like blaming Smith for chambering empty brass - couldn't I be the real cause of the problem?
Let's not forget that the gun is used and previously modified by others. And as for the magazines, it's a broad based issue that other makers have suffered - a lot. IIRC HK had that problem and it goes to two different specs floating around the world, which cause mags from one to not fit the other even tho on the surface they are both "M16." It's caused issues with Magpul and the Marine Corps about which specific ones they allow to be used in service. I don't doubt we share the belief that a "M16" mag should fit any M16 lower - but the reality is there is no guarantee. What happens is that the more successful mag maker goes undersized for the worst case situation - leaving the handloader with the shortest loaded length mag he may not care to use for his purposes.
Making broad brush comments over a makers reputation based on an anecdotal incident of one item in the hundreds of thousands in their product line basically tells me the owner has a limited and extremely short tolerance toward fabrication and assembly. It's actually NOT something you can buy with more money. I say that because if you were to purchase two watches both certified as chronometers by the Swiss, you could pay for a nice Rolex in an automatic movement or get a quartz for far less with half the allowable inaccuracy.
Just like the government was paying for a Colt but getting something twice as unreliable as an FN. Now add that in both sets of guns, you could find one in each that was better than all of the other Brand. And one that was the worst. We buy a gun and take it home - which one is it that I got? Me, one of the run of the mill ones in the middle, I hope. My feelings won't get hurt, nor will they get overinflated about how great they are and an unbelievable value.