I must be strange for saying this because so far I haven't seen anyone mention it (or I missed it), but without a doubt, SMASHBOX. I was a bit skeptical, but I bought their Real to Reel kit and I was amazed at how different the looks were and how great I looked (compared to how I do normally)
After that, I'd agree with others mentioning Bare Escentuals, it's light and easy to work with and looks naturally... I find that with B.E., I kind of look the same regardless of what colors I put on. Maybe it's my technique.
After that, I'd have to say that I'm a Chanel makeup wh*re... am I allowed to say that?