Lets see here: for an Ak 47 or 74:
Mags in 7.62 and 5.45x39 are cheaper
Ammo is Cheaper
Ammo is generally more lethal (at least in 7.62) and arguably in 5.45
AK in 223 has no advantage that I can think of.
Damien in Seattle
I don't list my guns - I know glocks, FALs, and AKs but I'm not sure my ability to fill a gunsafe with guns make me an expert on anything.
All that you can depend on from a 45 is that it will drill a .45 - .70 inch hole about 14 inches into someone. There will not be "energy dump", people will not fly backwards, and they will not necessarily fall as if they have been struck by lighting.