I've used Hallertauer Hersbrucker (not Mittlefruh), Saaz, Spalter, Tettnanger, and Magnum - All German varieties. I know there are some differences between the German and US varieties, but can't offer specific comments because I've only used the German varieties purchased at the LHBS. I've also used some Sterling in a Hefeweizen as a sub for Saaz with good results. Even a particular variety will differ somewhat with where it is grown because of variation in weather, soil, and other growing conditions.