I found the rocket launchign arm to be slow, and underwhelming. It replaced your grenade slot anyway, and seems to be less useful imho.. But, they dont require you to equip directly, like the other 3 cybernetics, and can be used while having another weapon equipped, at the cost of not having a grenade equipped. They do not scale well later in game, at all!
I found Gorilla arms powerful and extremely useful throughout, particul;arly durign street fight quests.
Monowire can feel powerful, but the monowire doesnt really fill a role that gorilla arms, or Mantis blades dont already fill. Making them quite redundant. They seem to have slightly longer reach, but thats about it. I did find them fun to use however, and did not try them later in game, so no idea how they scale.
I like the Monowire more than Mantis blades, but Mantis blades have far more support in the talent trees. Hopwever. swords are always stronger than Mantis blades.
Gorilla Arms>Mantis Blades>Monowire>Rocket Launcher