Hungarian Tankers are true surplus grade mags, best option.
But pricey these days and have been for a while. A tight fit in my WASR & Draco but a prefect fit in my AK63 DS.
Have had good luck with old Tapco 20s but they’re out of business unless their new owners are making more.
Magpul 20 round MOEs are good for a poly mag. Cheap, easy to find, good feed geometry.
As are the KCIs. I know they’re thinner steel than surplus but that’s not as big an issue with 10s & 20s.
One big plus for Magpuls and KCIs is they seem to fit all my AKs without any filing or fiddling.
One other option is cut down surplus 20s if you can find them. I cut down a dented surplus mag and while it works fine, It was a half day project for me. A guy on AK Files called Bad Element was cutting down surplus mags, not sure if he still does. And Arms of America had a batch of Grade 3 Romanian mags cut down to 20s, I grabbed some for a few bucks less than Tankers and they were done well.
Also have some Croatian 10s, not available in 20s, they’re OK but be ready to file, mine were made to two different specs, like they came from different factories or assembly lines. Heavier gauge steel than KCIs though but not as heavy as surplus.