Just my personal experience and should not be taken as definitive, but here goes:
1. I.O. Inc. Had some mixed luck here. One had functioning issues out of the box with a badly worn recoil spring (contrary to popular opinion AKM mainsprings do wear out - the one this shipped with was well over an inch shorter than a new unit and caused FTE issues) as well as a loose and poorly fitted gas cylinder. However it did clean up nicely into a replica DDR AKM circa mid '60's timeframe with a last gen wood stock. The other one functioned okay but has a badly made FSB. Got a spare FSB on hand, just need to get a little time on a shop press to push it off and replace it. Wood on that one was very poor and I ended up putting some AK74 wood on it for the time being. If the whole AWB 2.0 thing ever blows over I'd like to build up a real semi auto AK74 clone then redo this one as a regular AKM. Haven't seen a single one in our LGS that didn't have something wrong with it, but in the leadup to the November elections I was buying every AK I could afford and figured I'd sort it out later. Uneven quality. Can't recommend with a clear conscience unless you've inspected it personally and made sure its GTG. Make really sure the receiver pins are tight - seen some really awful riveting in some at the LGS. I picked the best of the bunch and still had some issues.
2. WASR - Haven't seen a bad one. All the talk about mag wobble has been h******** in my direct experience. Couple of my "dimpled" AKM's have as much or more wobble. Wish I could afford another, but the days of $550 WASR's are gone and my finances are reeling under obozocare. Canted FSB can be a problem on the WASR, but the CAI rifles I've had have been fairly easy to fix this when it happens - you just drive out the pins, lock the bbl in a vise and (with a wood block to keep from marring the FSB) tap it in the correct direction.
3. "other" - sometimes I see parts kits built up into full AK's, often using Nodak Spud receivers. The couple I own and others I've seen have been good, but they were through big vendors (i.e. places like atlantic) not ed the wannabe gunsmith in his basement.
4. Norinco - Norcs were good quality pieces, but are preban unless its a Mak90 with the thumbhold stock. The thumbholes work okay, but look goofy. If a Mak90 is converted to a military configuration, watch your 922r parts count - no more than 10 of the "magic pieces" can be imported, and while its true that the person who puts the 11th piece in is the one who's on the hook, the feds can seize a rifle claiming a violation (i.e. the gun is contraband even if the owner is in the clear). Magazine counts as 3 pieces, so if you have a piece that's over 7 w/o magazine that can be a problem. Tapco followers will lower your overall count by one, and if you're using imported polymer mags there are also US made baseplates that will knock another piece off your overall count. Typical parts to replace inside the piece are the pistol grip, the gas piston, and the muzzle brake. On any AKM, if you have one with a muzzle brake/nut that's welded on, it counts as one part with the bbl. As soon as the weld is undone, then you've got a second piece.
5. Poly Tech - Stellar pieces, but preban and $$$$$. Wish I'd never sold my AKS762 over 20 years ago to pay the rent. Terrific fit 'n finish for an AK, takes a little getting used to the permanently attached bayo, but its worth it. FCG had this crazy gold colored metal plating that was a little slippery and didn't chip or peel. Really top notch, but $$$$$.
Chinese made AKM variants have a thicker sheet metal and are generally very very sturdy. Chu wood stocks ain't pretty but they hold up well and once you get used to that blond wood you ditch any dumb ideas about swapping it out. Serious collector pieces. If I get my hands on another thumbhole MAK90, I'll leave it alone. Its a part of history showing our dumb*** gun laws in action and a bit of a rarity among AK pattern rifles because of this.
!!!!IMPORTANT!!!!! One thing to watch out for on Chinese AK variants is the dreaded "3rd hole special". A handful were shipped in with the auto sear hole drilled and either a rivet placed through the hole, or the axis pin welded in place. Don't confuse this with the center support pin, the axis pin for the auto sear is below this. RHS rails had their notch filled in with weld metal, which is another dead giveaway if you strip the piece to inspect. DO NOT BUY ONE OF THESE EVER. The BATFE has a list of the serial #'s and its not worth 10 years of institutional food to get caught with one. Its a case of their stupid "once a machinegun/always a machinegun" rule, which is the same reason to stay away from M2 marked carbines. Even if one only has correct semi auto parts, the fedskis will burn someone big time on this. YOU ARE WARNED.
Okay, sorry for being all scary there, but its something every budding AK guy needs to know. All us EBR guys are on the edge of a precipice - fedskis would love to push us over, and if we give 'em even a shadow of an excuse, they will. Keep it clean is my advice, whether its an AK, an AR, or even a mini 14.
4. Other AK variants to consider
a. RPK - best of the breed if you can find one is the AE10B; its got the true RPK pattern receiver with the thicker metal and oversized trunions. Stay away from the AE10, unless you talk 'em down on price, since the earlier AE10 had a pencil bbl and standard AKM receiver/trunion configuration. Love my AE10B, since with the heavy tube it doesn't heat up as much as a standard configuration. Bit of a beast though - length and weight are comparable to an M14. But man does it handle heat build up well. If you get one, make sure to stock up on 75 round drums!
b. AMD65 - pretty awkward looking compared to a standard AKM and can suffer from canted FSB to a greater degree (shorter sighting radius makes this a problem). Heats up fast and damn' does that sheet metal handguard get hot. Keep your hands away from it. Folding stock is a little delicate so be careful! Expect to get looks on the range since no one will know WTF it is. Also expect others on the range to keep far away once they hear the muzzle blast off that shorty tube with the permanently welded brake for length compliance. If you get one and the pistol grips suck, Roningrips makes a terrific set of grips (you need to order two grips). Not the standard hollow configuration grip, Roningrips are solid with a hole drilled for the bolt. Very strong, recommended for AMD65 owners.
If I only had one AK, it would be a standard configuration piece. But the others are fun too.
Whatever you get,
Enjoy.
Grumpy
