Colmar or Mulhouse?

Unless you are interested in the train or antique car museums, I would give Mulhouse a miss. I did not fine it attractive at all.
Colmar can be reached by bus from some of the surrounding, pretty villages - Riquewihr, Eguisheim, Ribeauville, Kaysersberg - though I do not know if they run late into the evenings that time of year. It is a very pretty area.

I haven't visited Mulhouse, but never read anything that would make me want to go there. On the other hand, I've visited Colmar a couple of times, and Alsace overall several more times. Colmar is definitely worth staying in, and a trip to Strasbourg would be worthwhile, especially during the holiday season. One time we stayed in Riquewihr and got there by bus from Colmar. I believe there is also bus service from Colmar to several other villages between Colmar and Strasbourg.

Mulhouse is long on history and short on charm. Colmar is the opposite. Of interest to me in Mulhouse were the four museums and the examples of "humane" worker housing that influenced that movement greatly. Mulhouse was an industrial center. Colmar is beautiful and a tourist mecca especially at Christmas market time. There is also the splendid Isenheim altar. For your purposes and in light of your interests, I think Colmar is the better choice.

I've been to both Colmar and Mulhouse (the most recent trip earlier this month). While I believe Mulhouse has a decent central city with lots of commerce and lively pedestrian presence, I don't believe it would be as attractive to a short-term traveler as Colmar would be. Probably a better place to live permanently, but not to visit for a few days.

I suspect the price discrepancy you're seeing reflects demand, and there's a reason for that discrepancy in demand among visitors.

If you're in that area, a short trip to Belfort to see its citadel and learn about its history might be worth your time. There's a big lion sculpture there by Bartholdi to commemorate events in the Franco-Prussian war (he was the same sculptor for the Statue of Liberty in New York and the monumental, recently restored, Fontaine Bartholdi in Lyon's Place des Terreaux).

Strasbourg ?? Also filled with Christmas markets, and direct train from/to Paris.

I visit Mulhouse every couple of years for the car and rail museums - both are absolutely world-class, not just regional attractions. However, if you aren't interested in either, go to Colmar, which is much more picturesque.

Colmar Was overrun with tour busses my wife and I didn't like it. the canal was full of tour boats there was so many people you couldn't even walk without running into other people it was really annoying too bad I look like a cute little place maybe on another day where there were few people whenever that is.

Our Alsace time was spent in around Barr. A beautiful town, beautiful area, affordable, friendly, uncrowded and just a short train trip from Strasbourg. Just throwing it out there as an alternative.

I thought Colmar was nice. I thought the smaller towns around Colmar were nicer. Colmar was too big and busy for me. We stayed in Colmar one night and then went to a smaller town-Eguisheim. In Eguisheim we had very lovely BnB in a winery for a very reasonable price. We really did like the place we stayed in Colmar and it was VERY reasonable. It also was in a working winery. It was charming and quirky, staff was great as was the breakfast. It was called Maison Martin Jund.

A year ago in September I was not so much impressed by Colmar, it’s quite a big place and I missed the intimate feel that makes those places with half-timbered houses so special which you can find in the other smaller ones. Think for moving around with public transport Colmar is well located.

I think it’s worth looking for a hotel or B&B like in nearby Turckheim, easy to reach from Colmar. Speaking for myself I would avoid staying in the well-known places, mostly overrun and to my feel way too commercial, but again that’s my idea. Stayed like lplebusque20 near Barr too and I agree with the description, market square with city hall is really lovely.

Ofcourse you can go to Riquewihr, Kaysersberg etc., they are lovely but I was actually more charmed by Bergheim that was more authentique to me, the same for Kintzheim just a few km from Kaysersberg, there are a whole lot of these places in Alsace.