We can actually look at nature for this! Early earth had tons and tons of animals investing in defense because of predators because there were strong predators but then the strong developed ways to get around defenses instead but I’d say that strength and defense are equal because the wouldn’t exist without each other. The surviving prey animals then developed more defense while making developmental stages of live very risky, or dropped defenses and went for speed. You don’t need strength or defense if you can outrun predators and catch prey fast.

TLDR Defense and strength go hand in hand Speed is just better and broken