I used Bare Minerals for about two years. Towards the end it started making my skin itch. A friend recommended Everyday Minerals and I've had good success with them. They give you very generous sample sizes and have a very wide range of foundation shades to choose from. They also have several different finishing powders and concealers.
For more information on what to look for in mineral makeup, check out this article:
http://www.natural-beauty-info.com/mineral-makeup.html