I still prefer my AR platform rifles. They are much faster to reload, have way better ergonomics and higher accuracy potential, but the AK's work and are plenty accurate for a "combat" rifle. I added red dots to all of them. For a handguard/rail the RS Regulate is light and good enough to mount a light and vertical grip. It also helps with keeping the rifle cooler since the platform gets hot quick. They have good ventilation. Ultimak works for both red dot and a light and it holds zero. Some people worry about heat on the optic. I never had an issue. I run side mount optic mounts on the rifles that have them in RS Regulate mounts. They also hold zero and return to zero well.
I have both AK47 and AR15/M16 - Both are good combat rifles. If I knew I was going to be living in the mud for 3 months without a cleaning kit or opportunity to maintain my rifle as it should be, I might choose the AK. Mine is dead reliable and far more accurate in the hands of a trained marksman than people give it credit for. My AK47 has the best trigger of any mil style rifle I own. I would not want to be on the receiving end of one inside of 200y. But...
Compared to the AK, the AR15 is lighter, faster, more controllable, easier to engage multiple tgts with controlled fire. The safety and charging handle are more ergonomic. The ammo and mags weigh less. Keep it clean and lubed and the AR15 is also dead reliable and unless you are in an extended fire fight it is not an issue and even then, as long as you clean it after use, it is a good rifle. The only failure I have ever had with one was a gas tube that split on a short bbl upper being used for full auto fire alot. The normal length gas tubes are not a problem and the FAL-like gas piston uppers are even better.
The AR15 is a dirty action, but as long as you are able to clean and re-lube it after use, it is reliable. The gas rings wear out if you shoot it alot but they are cheap and easy to replace and it will run OK even with them in bad shape. If I was told that I was going into harms way, would be shot at and have to defend myself from others and could only carry the AR or the AK, I would choose the AR. If I was going to shoot in a IPSC 3-gun match and could only choose one, I would choose the AR. If I was competing in a NRA hi-power style precision marksmanship match and could only choose these two options, I would also choose the AR15. AR15 is faster to make a 2 shot double tap at close range but I would also offer that the AK47 might not need a double tap to be just as effective. One well placed 7.62/39 might just be equal to two well place 5.56mm? The newer SS109 ammo might also reduce the need for dbl tap in a real world enviro. Just saying, some of our own BS must be shoved aside to perform and objective assessment. Think about it. They both will trump a spear. The M16 is more controllable on full auto but even so, it very tough to keep more than the first two shots on a humanoid tgt at 50y or more. It is fun but mostly useless for both of them.
If I was going to be in a outdoor survival situation for 6 months to a couple of years with no end in sight, and would have NO opportunity to clean or maintain my rifle and was expecting to use it for hunting, self defense at close range, from both humans and large predators, (Brown Bear/Big Cats), would be out in the elements in blowing sand, mud, snow/ice, rain for a very long period with no chance to RTB for R&R, I would seriously consider the AK47 but would take the FAL over both of them.