A study in Frontiers in Physiology found that optimizing training to velocity- and force-deficits led to greater increases in jump height than a well-balanced plan.
For those athletes with a velocity-deficit (strong but move slow), speed training leads to positive results.
For those athletes with a force-deficit (move fast but weak), strength training leads to positive results.
Find out what your weakness is (strength or speed) and train that ability.
You can use force-velocity profiling to get this done or use your own judgment. If you are average at everything, then use a combination of strength and speed training.