I like the square pots I can get at my local nursery. Plastic, durable, and white. The white, I figure can only reflect more light to lower branches and the square shape means you have no gaps of wasted space.

I went with standard red clay pots for my first grow and after 3 weeks, had to keep wiping down the outside with a bleach/water mixture because Etiher mold or mildew started forming on the outside of the pots. Didn't hurt the plants, but what a pain in the ass!