If you have too much gear to choose from, you'll busy your mind with thinking about what camera or lens to use, which in my opinion is counterproductive. My best results always come from sticking one lens on one camera, and force myself to work with what I've got. It allows me to let my imagination work full time, and to be ready when the moment approaches.
My favorite two MF lenses are a 50mm and a 110mm macro. You can cover a lot of ground with one wide angle and one normal lens. Real easy to carry, too.
Am I really the first person in this thread about Cuba to use the word cigar?