I haven't shot a AK74. I think regular people shoot AK47's more for the nostalgia, popularity, and cheap ammo. Most probably don't know the AK74 exists. I'm thinking AK74's are more for the enthusiasts who are more knowledgeable, who also like the nostalgia (otherwise they'd be shooting AR15's) but want the better performance and are willing to pay the price and inconvenience of getting 5.45 ammo.
I bought an AK47 mostly due to the cost effective (cheap) ammo and was readily available and I just flat wanted an AK
I had always planned on shooting it more, but just have been spending more time with ARs.
74 is an overall better battle weapon for causing enemy damage / casualties. Overall magazine weight is lighter and the round is more devastating to soft targets. Also has a better natural range than the 47, which usually has an effective range of >400m.
if the 47 is a cleaver, the 74 is a butcher knife, while the AR is a scalpel (allegedly).
Regarding the performance of the 5.45, what you said is kind of what I'm gathering. I had always assumed it wasn't vastly different from the 7.62x39 and basically just saved weight. But like anything, why come out with something new if it's not better. Would be interesting to do a personal test of all three guns, assuming similar set ups. Might be difficult due (if not impossible) to differences in ammo available for each and opinions on what is a good ammo to compared the three guns on. Still would be interesting to try and from a perspective that doesn't already favor one going into the tests, which many YouTube videos seem like.
If the availability of the 5.45 was akin to the x39, I think overwhelmingly there would be more 74s than 47s.
I know I would go 74 all day long if that was the case.
Less recoil, flatter shooting, slightly more accurate.
I haven't shopped around for 5.45 since I don't have a gun for it, but I also don't recall it being that readily available as well.
I was discussing with a buddy in NC and another in TX. My buddy in NC has a 74 and he said he had a bunch of steel core ammo (that has since been restricted from import, at least from what he tells me) and that the mil-surp stuff that he sees is corrosive and not very accurate in his experience. That would suck if the ammo is corrosive. At least for me since I don't want to go rushing home to clean the gun every time. Maybe he just needs to find better ammo.