Ladies (or men if it's your thing)- what are your favourite makeup brands, what products do you like best in their line and why?

As a makeup artist, I generally only use the cosmetics brand when doing makeup for clients. I do this mostly because it looks a bit more professional rather than having 200 different brands in the case.

Although I only use the one brand for my clients, I believe that each cosmetics company has their strengths and weaknesses within their line of products. When I buy makeup for myself or friends, I tend to take bits and pieces from various brands. I continually try and use different products and brands in order to reach “makeup supremacy!” lol.

So, to assist me in my quest to find the best products out there I want to know:
What are your favourite makeup brands, what products do you like within their line and why do you like those particular product so much?