Ditto what NMshooter said...the brake of choice is probably the Soviet-designed "AK-74 style" brake with the two BIG square holes in the side at 3:00 and 9:00. On my shooting buddy's Romanian 5.45 AK the sights will stay right on your target while you're slapping that trigger as fast as you can; on my bare-muzzle 5.45 AK there's noticeably more muzzle climb, but not enough to be an issue for me. It should help more on a 7.62 AK, not so much for reducing recoil as for reducing muzzle-flip for rapid follow-up shots as in 3-gun competition. Personally, I'm leaning toward having a Vortex flash-hider put on my AK instead of a muzzlebrake, since the recoil in 5.45X39 is so low that I don't feel I need the recoil reduction, especially at the price of louder muzzle-blast. Either a brake or a FH is a good idea on a "rough-duty" gun, since they will both protect the muzzle crown from damage.
If you're buying a new "post-post-ban" AK, check the front sight base for a plunger at 12:00 - it's there to lock the muzzlebrake in place so it doesn't unscrew itself. Ideally, you should be able to push it in with your fingernail or a punch - that way, you can unscrew the brake for cleaning. If the brake had been soldered on for AWB-compliance before the sunset last year, either pass on it for a newer gun or try to bargain down if you just can't live without that specific AK.