Not quite as simple as milled vs. stamped. Mainly because you have two major different stamped receivers right off the bat. The 1mm AKM and the 1.5mm AK
First off the AK-47 was designed for stamped receivers, but Uncle Joe was having some quality control issues (mainly in the heat treating dept.) So that's how the milled receiver came to be. The original AK has a thicker barrel. They finally went on to stamped receivers and still retained things like the thicker barrel and used a thicker receiver, a good example is a Chinese type 56 or MAK-90. Eventually the AKM-47 came along, it used a lighter barrel and thinner receiver, which helped shed some weight. The AKM is the most common one found worldwide and has more than proven itself.
As far as the general opinion goes, most agree on the internet that the milled/stamped AK hold some accuracy and service life over the stamped AKM, but also agree that it's negligible. Personally I wouldn't worry much about the life of it as an AKM is expected to be in service 30+ years under relatively harsh conditions. That's the military FA ones at that. There really isn't much stress put on the receiver itself aside from the bolt carrier banging around in it and the forces put on the axis pins by the FCG. All the real pressure is between the barrel and the trunion lugs. I'm kinda suprised no one has milled one from aluminum with steel rails put in it.