What anatomical unified provides the most protection to underlying tissues?
Answer:
I'm not certain around this, but I would tend to think cartilaginous joint because they tend to cushion and support load-bearing joints that primarily function contained by postural stability and thus must be able to withstand great force -- e.g. knees, fibrocartilage between intervertebral discs
Sutures are natural joint protecting the cranial contents.
Fibrous,cartileginous and synovial joints of limb facilitate movements more than protecting soft organs.