Germany is the home of Christmas markets and Dresden is the original market, but Nuremberg is a very well-known market, probably the best known of all (the Christkindlmarkt). It is however mobbed with tourists, but there are many others in Germany as pretty much any town of a good size will have a market. If you did want to see the German markets try posting in the Germany forum and you will get lots of answers. You could pick markets in a given area (for instance Bavaria, or the Rhein-Main district) and just stick to that to make travel easier. Germany has a fantastic rail system so it will be easy to get around by train. It might help to pick somewhere you actually want to visit in case you are "marketed out" - then you can just turn to local art museums, etc. So in the Rhein-Main version you might go see Frankfurt, Wiesbaden, Mainz, Rüdesheim, Cologne (where there are 7 markets, a world-class cathedral and lots of museums and brewpubs but alas dismal / boring architecture), Michelstadt (which is a very small market popular with German tourists), Limburg, Idstein (5-7 December 2025 only). Those two last ones are a bit off the beaten path but they are cities with amazing Fachwerk and if you are seeing the region they would make a nice stop. Make sure you get to the markets at night as this is when they are at their best.
People also rave about the Christmas market in Strasbourg (in the Alsace, France, which has been German territory at times), but unfortunately I've never been, so can't comment on it, but I'm sure someone else here can.
Lavandula