High effciency T8's with chrome reflectors. The light is whiter which makes it appear brighter. I only have three fixtures in the front side of my shop right now (1200 ft) and it is plenty to work. I am going to double it when I get a chance to run some more pipe and hang them.
I had (8) 8ft T12's with no reflectors in my old shop that were not as bright as these small fixtures.
Reflectors behind the lights is key to getting all of the light from a florescent. Without good reflectors your getting 60% of the light they are putting out and the rest is just absorbed into the surface under the bulbs. Light colored walls, as mentioned, helps alot too. BTW, I was an energy engineer in a previous life and we used the little T8 fixtures with reflectors in buildings all across the US.