The Engineer has access to a Combat Drone and a Turret. There seems to be some minor differences between the two but they share a cooldown. Is there a reason to spec one over the other? Should leveling both abilities be avoided since they share a cooldown and perform a similar function?
The combat drone is offensively oriented and seems to be typically way better at distracting large targets than the turret as it can, and will, move in close and start zapping away. The turret is a lot more defensively oriented, designed to hold one spot on the battlefield or protect your flanks, etc.