what anatomical joint provides the most protection to underlying tissues?

Question

is it either a fibrous, cartilaginous, or synovial joint?

Answer 1

I'm not certain about this, but I would tend to think cartilaginous joints because they tend to cushion and support load-bearing joints that primarily function in postural stability and thus must be able to withstand great force -- e.g. knee, fibrocartilage between intervertebral discs

Answer 2

Sutures are natural joints protecting the cranial contents.
Fibrous,cartileginous and synovial joints of limbs facilitate movements more than protecting soft organs.