Watercolors
i've only been working with watercolors since 2009. before that, my only other experience with it was a class in college. it's now my favorite medium, but it is incredibly challenging.
my favorite brands are winsor & newton, kremer pigmente, daniel smith, m. graham, schmincke, maimeri blu, and holbein. some shades in one brand are better than others, so the best way to find out if you like them is to try them. a great resource is bruce macevoy's handprint, which provides you with a wonderful starting point on which pigments will serve your art best. what he said, do.