Anything in original AK format. Tolerances are loose where precision is not required, and the healthy case taper means extraction is always a cinch. The AK/AR hybrids lose some in reliability that they gain slightly in accuracy. But at the yardages it was intended for, any AK should have little problem shooting minute-of-man accuracy.
I have an M&M AK and never had an issue.
If you want the cream of the AK crop and are not wary of a $2600 price, the Rifle Dynamics build with the Sharps Bros. milled receiver not only keeps the legendary AK reliability but also adds sub-MOA accuracy.
1) Chinese Polytech Legend (Chinese T56) - smoothest action and trigger of any AK47, durability and reliability are proven in the fields all over the World
2) Finnish Valmet M62 - another high quality milled AK but with Finnish accuracy
similar to my M76 rifle but with a milled receiver and in 7.62x39...
3) Bulgarian AKT-47 - a third milled receiver AK with durable polymer furniture and proven reliability around the World.
AK from a real factory with a warranty is the obvious choice. If an AK is built badly there ain't a whole lot you're going to do to fix it.
If 7.62x39 is a requirement, check out the Galil ACE made by IWI. Milled receiver AK with paint over parkerizing for a finish, plus it comes with tritium iron sights and is easy to mount optics on.
My current favorite 7.62x39 rifle is my vz58. It's lighter than an AK but softer shooting and it feels light and lively to handle. Proprietary mags are a downside though.
The AK and vz58 can mount optics with a side rail, but choices aren't as vast.
Here's the SA vz58 rifle. These have great triggers because it's a striker fired design.
Another interesting Czech rifle in 7.62x39 is the predecessor to the SA vz58, the SA vz52/57. These did have issues with cracked stocks, though, so it wouldn't make the top three for durability.
I have a dirt cheap, bottom of the barrel, Romanian AK-47 and have no complaints about it - it has always functioned perfectly. Spending high $$ on an AK platform seems counter intuitive to me - the whole point of the guns is cheap, reliable, and simple enough for the average third world child to operate.
I also have a late model Ruger Mini 30; I prefer the cheap AK. Never been much of a Ruger person.
I'm new to the AK world. I just bought a Riley Defense made in USA stamped receiver AK-47 new for $630. I haven't shot it yet, but I'm picky about wanting to buy USA made products so I got this one. The cheap ones weren't that much cheaper and of course there is always more expensive... I picked up some Wolf ammo 7.62X39 for I think 6 bucks per box at the same time. I live in VA and they're talking about a ban, but will let you keep what you already have if it goes through. Don't know about high capacity magazines so I won't buy any now until I see what happens; I'll just use the one 30 round Tapco polymer mag that came with the weapon. It seems well made and I'm really impressed with the simplicity of these. I bought a Colt M4 AR-15 about 10 years ago and it was a good bit more expensive than the AK.
I hate to say so, but the Riley Defense AK47 rifles are not very good. Certainly not as good as even the cheapest imports. Check out the AK Operators Union test on this rifle on YouTube. Maybe you'll get lucky and get a good one, though.