Only accurate rifles are interesting. Not my quote but I believe it.
With that, the AR15 wins hands down.
I always respected the .223 cartridge but when handed an A1 in basic training, my first question was "where's the scope?". I couldn't believe they expected me to shoot a 350 yard pop-up with a freaking aperture and post iron sight.
Well, I had grown up with firearms and practiced daily by keeping starling populations in check. I managed to kill one at 90 yards with an iron-sighted pellet rifle. Something 6 times larger at 4 times the distance shouldn't be a problem. I never missed a 350. It was those ill-maintained, shot-out 25 yarders that didn't want to fall.
Later in my Army career, I had a chance to shoot an AK on an Army range. It was much cruder and the only reason I got some of the 300+ shots was due to the volume of sand the short-falling bullet would kick up and trigger the hit.
They might be reliable but the first shot isn't reliably on target.