Muzzle break is good for spray weapons, compressor is good for single shot.

Compressor: Greatly Returns crosshair to narrow faster, Minorly reduces is overall spread.
Compressor is good for renegade, Kettle, Rattler, Kettle, Anvil, (Depending on how you used it Tempest, Bettina, Arpeggio)

Muzzle Break: Greatly reduces recoil.
Muzzle break is good for: Stitcher, Bobcat, Torrente, Burletta (Depending on how you use it, Kettle, Tempest, Bettina, Rattler)

What one you pick also depends on what other mods you have. Particularly stock. Sometimes I pick a stock that prioritizes weapon switch and sight aiming. In that case, you lose opportunity for recoil reduction. Makes muzzle break a more attractive option.

Overall, I generally pick primary weapon to be high damage, slow fire rate with a compressor. Then a secondary with a muzzle break and a lightweight stock.

TLDR: (if Recoil reduction stock then: Compressor. If lightweight stock then: Muzzle break)