Erfurt or Leipzig?

Our plans changed mid-drive and we ended up staying in Erfurt. I had no idea what to expect but found it beautiful. We spent hours walking around and part of the next day. Outstanding architecture, churches, a medieval synagogue, a picturesque bridge and many Luther sites. Very happily surprised with our stay. We’ve never been to Leipzig. We stayed at the Mercure Altstadt …very well located, parking and it had a gigantic breakfast buffet (pre covid). Safe travels.

The two cities are not really comparable. Leipzig is also important for the fall of the Berlin Wall, etc. It has an excellent art museum, and some literary-related sites. You may find Weimar to be a desirable stop. I believe that J.S. Bach's birth house in Eisenach is long gone.

Not related to Luther, I'd mention the UNESCO WHS Dessau-Worlitz Gartenreich and a bit farther, Quedlinburg. I was interested in the Karl Zeiss museum in Jena, but we didn't have time. Lots of people talk about BMW factories, but I wonder about Leica camera factories?

I found the Stasi Museum in Leipzig absolutely fascinating. I also loved St Thomas Church.

I believe that J.S. Bach's birth house in Eisenach is long gone.

True, but that's like the stable in Bethlehem - because only enough people have believed in it intensively for aeons, the house on the Frauenplan is now "the" Bach House. And it houses a beautiful museum.

but I wonder about Leica camera factories?

You have to go to Wetzlar for that.

I suggest you go to Leipig for diversity. It has more a big city feeling than Erfurt, and you already have two smaller cities on your itinerary (Eisenach and Wittenberg.) Both places you mentioned (Bach and Stasi museum) are must sights. If you are into music then check out the "Notenspur" trail. Pick a few of those places, definitely Mendelssohn house. And a bit of (window) shopping won't hurt either, and Leipzig's arcades (Passagen) are perfect for this.

Difficult choice between Erfurt and Leipzig. I think both are pretty great.

Erfurt

• Made it through the war relatively unscathed ==> great architecture
• Domplatz is super cool
• Erinnerungsort Topf und Söhne -- museum in the old administration building of the Topf und Söhne manufacturing company, that as a tiny part of its manufacturing portfolio built the ovens for Auschwitz and other death camps -- museum explores how a "normal" company with "normal" owners who even shielded some Jewish employees became complicit in genocide
• The Old Synagogue -- most parts date to somewhere around 1250-1320 AD
• The Merchant's Bridge
• Luther sites
• Has its own Stasi Museum that includes the Stasi prison. I didn't make it there but it has good TA reviews: https://www.tripadvisor.com/Attraction_Review-g187419-d6989386-Reviews-Gedenk_Und_Bildungsstatte_Andreasstrasse-Erfurt_Thuringia.html
• Great Parks
• Anger One -- a former Jewish department store that was removed from its owners and given to Aryan owners -- now home to Karstadt and other stores
• Sites related to West German Chancellor Willy Brandt's visit to Erfurt in 1970. Brandt was the first West German chancellor to visit East Germany, and Erfurt was the site of the visit. He was greeted enthusiastically by the Erfurt populace, a huge embarrassment to East German officials. https://www.youtube.com/watch?v=J2FeoG2PaDU&t=194s
• Great hotel: Hotel Domizil on Domplatz -- owned by mother and son -- son is a chef and makes wonderful breakfasts

Leipzig

• Thomaskirche and its Thomanerchor (boys choir)
• More interesting to me is Nikolaikirche, where Monday Prayers for Peace started in 1984 evolved into Monday Demonstrations in 1989, leading up to the Oct 9 1989 Monday Demonstration that was surreptitiously filmed and then later broadcast by West German tv to East Germany, leading to more Monday Demonstrations across East Germany
• Monument to the Battle of the Nations -- one of the most amazing human-made things I have seen
• Certainly not a "must see," but the former Soviet Pavillion at the Alte Messe has some pretty cool imagery on its facade
• The train station itself is gorgeous -- one of the biggest in Germany
• The Passagen
• The Stasi Museum
• Bach sites
• The skyscraper with a rooftop restaurant

Which to pick? Both offer a rich experience, but I lean toward Erfurt because of the town's architecture.

I would suggest going to Leipzig after visiting Erfurt and the Luther sites, if you can make time for this cultural and historical city. Leipzig is famous for its music history, the houses/museums of Mendelsohn, Schumann, Bach, are there, plus famous for the Leipzig Gewandhaus Orchester. I've been to Leipzig a couple of times but only as day trips from Berlin and Dresden, obviously only saw it superficially.

Historically, it was at Leipzig where Napoleon was finally defeated, overwhelmed by the third day by the Allies. The huge monument commemorating that battle the Voekerschlacht Denkmal can be reached by taking the S-Bahn from Leipzig central station. A small museum on the battle basically from the perspective of the Allies is next to the monument.

In April 1945 the Americans got to Leipzig, took it before the Soviets arrived.

As others have said, they are both wonderful. And I think the lists of possible things to visit you have gotten in both are fantastic. I cannot think of what to add.

I suppose that I would say that it really depends on if you want to see a bit more "city" on your trip, in which case I would chose Leipzig. Beyond the museums etc, it is also simply a good example of a normal German city, and gives a good atmosphere contrast to the smaller places you will be visiting. I always enjoy visiting such places in other countries when I travel, to get a sense of what life feels like in a variety of places. But if you are already well-familiar with this type of city, then it just comes down to which set of attractions are of greater interest.

Weimar is wonderful if you can spend the night
ir really clears out of tourists in the evening

Leipzig was ok in our books
more spread out but
also interesting

was just there last week to both