The Kühne medium mustard is fine. Another option is
Develey. (Kühne and Develey are about the same as far as quality is concerned. Minor difference in taste, you have to try them to see which one you like better.)
The best Weißwurstsenf is
Händlmaier, without question. It's
available at Amazon.
Another German hot mustard worth trying is
Löwensenf Extra. Also
available at Amazon. I believe it is no longer as hot as it used to be half a century ago. Either that, or my taste buds are burning out.
For a really hot mustard, try
Colman's Hot English Mustard.
The Maille Dijon mustard is good, I use it a lot. But I also recommend checking out the various
Dijon mustards by Edmon Fallot. As well as plain Dijon mustard, they make versions with grains, horseradish, walnuts, pinot noir, and more. They are all excellent.