I have the WASR-3, and have plenty of experience with it ( unlike many people who just parrot what they read online). First and foremost, I would prefer you buy where you can actually inspect before purchase. That goes for any AK variant. Look for the obvious first (canted front sight, mag well opening etc..etc). Before purchasing mine, I researched about it and found out about the wegner mags. So when I went to my LGS, to my surprise, I found out that mine came with a wegner steel mag, and an orange plastic bakelite mag.I told the salesman, that I wasn't too trilled about the orange mag, and if he could do a switcharoo from another box and get both wegner mags. He agreed! So I walked out the store with two wegners, and ordered two more online. As usual with any weapon I buy, I deburr any shavings and machine marks from the crucial parts, like firing pin channel, bolt assembly, trigger parts and gas piston. First box was gold medal for accuracy reference. I was surprised at the accuracy of this specific rifle, considering the loose tolerances platform. Everything after that, is being the cheapest ammo I can find. To this day, it has not jammed once. I do slow fire, and rapid fire. I clean it after a range visit and lightly grease the bolt assembly and piston.
I cannot speak for the AK-74, but I have read good things about the cartidge performance and value of ammo.
A good firearm, is the one that puts food on the table.