Comfortable bars are mostly a function of the riders size.At 5'7", I change most every bike to lower bars. A method of determining what works, which I read somewhere years ago, is to sit on the bike with eyes closed. Get comfortable. With eyes closed reach for bars. Open your eyes and get bars with grips 1" farther forward and 1" lower than your hands. This has worked well for me for many years. Unless a fairing or large windscreen is fitted, in which case totally upright is comfortable.