New Shop. Which lights?

18x40 building and how high is the celing?
I have 2 4ft 4 bulb T5 flourescents in the work table area, which is 15x15 area of a 30x40x14 building. I have 2 skylight panels, and then 2 400W metal halides with diffusers for when I am in the shop at night.
I friend has a 50x50 and he put 10 of the 4ft 4bulb T5s thoughout, and it lights it well. T5s are super efficient, quick to light, and don't give you a headache after being out in the shop all day.