I used to be a total d/s girl, aside from a few clinique and EL things that my mom bought for me, but I am pretty much a high end convert for the most part!
I love MAC because...
*They make fdtn shades light enough for me, and the undertones aren't bright pink or orange. Pale shades are really hard to find in the d/s
*The e/s have great, unique colors, and while I agree that some may be a bit too much for most people, they have really interesting shades that look good with the lighter colors they make. I plan on buying more of their more neutral/matter shades in the future. D/s matte shades are almost always too chalky and come off when you try to blend them.
*I like the one on one advice I get from the MA's. There is one girl I really like at my counter, and last time I went, I told her what I wanted (a sheer pink lipstick w/ no shimmer) and she was very happy to help me, and sanitize the lipsticks and tell me what she thought. Some that were not right she came out and said it, and wasn't pushy at all. I could tell she was being objective and wanted to sell me something that was just right.