Calf or thigh muscles for basketball?

which muscle group will give you the most jumping increase if you put the same amount of time into the workout? I'm trying to increase my vertical jump height and i'm wondering how effective thigh (i know there called quads) workouts would be. i've been doing calf workouts for about 3 years and have got about a 6 inch increase but i haven't worked out my quads any. so anyway,which muscle group is better for jumping? and how much better?