Obito is taller than kakashi here, as an artist that knows a thing or two about perspective i say that the closer a given object or person is to the camera or observer the taller they will appear. In this case we see obito standing behind kakashi. His eye and shoulder level are above kakashis slightly, even though kakashi stands closer in perspective of the image. Ths leads me to believe obito is anywhere from 2-3 inches taller than kakashi or around 6 cm. and we all know kakashi is a tall guy and was fairly mature from an early age. Leading me to,suspect obito to be fairly tall as well. As for minato I can not agree because he is sitting down clearly lol