In theory, those built and imported in factory configurations should be the most reliable as they are using mil-spec parts (for their country of origin). Which may or may not be better than commercial conversion parts that are US made.
However, that means they will have to be pre-1989 imports and those are quite a bit more expensive than 922(r) modified guns.
Based on what I have read, the Arsenal guns seem to be the most well regarded in the "new gun" realm.
I don't have any personal experience with these.
My experience is only with a Chinese AKS 762 Galil style side folder and a Hungarian Milled reciever select fire rifle with a fixed wooden stock and a Hungarian AMD Century build with a single strut wire folder.
The Century AMD was EXTREMELY LOUD with the muzzle brake and the single strut folding stock was nearly impossible to get a conventional cheek weld to and very painful to the cheek to shoot. It also had a problem with the bolt carrier hanging on the top of the hammer.
If I were going to buy one today, I would get a Arsenal 107 series that has the Bulgarian style folding stock. It is WAY more comfortable to shoot a fixed stock AK and this folding stock is basically a fixed stock that will fold.
http://www.arsenalinc.com/usa/SLR-107_SERIES/