Fisher price gear box's

What are the best gear boxes for the Fisher price motor (besides DeWalts)? I know andymark has some god ones but i was trying to explore some other choices.

In past years I know that we have used Banebot gearboxes. Normally P60s for 540 and 550 since the motors are about the same size.

Other than being a bit bulky and needing a bit of work to interface with a shaft, the stock KOP gearboxes work pretty well for lifts and arms.

AM Planetary -> any CIM gearbox works well