I prefer bar ends when using bars that flare, like nitto randonneurbars. I don't like how brifters mount at an angle, which changes the feel of shifting. I prefer brifters for normal bar styles though. The relatively shallow drop of rando bar styles tends to keep your torso at the same position whether your hands are on the hoods or holding the end of the bar (to shift)
Also, I prefer either over downtubes shifters because I like to maintain contact with my bars while shifting.