Slant brakes are primarily used to give the AK-47 an "authentic" look, plus they are the only muzzle device that permits the mounting of a bayonet on an AK-47. None of the preceding is true for AK-74 rifles.
I have heard good things about this muzzle device:
JTAC-47 Compensator for 7.62X39 AK, 14:1, LH
This isn't just a copy of some other brake that's been adapted to fit on an AK-47. AK Concepts designed this as a serious muzzle device that is aimed at function more than just a US compliance part.
AK Concepts designed a compensator that not only lessens the recoil of the AK-47, but does so without a significant increase in blast noise directed toward the shooter or individuals next to the shooter.
This compensator fits all standard AKs with the 14:1 LH thread (reverse thread).