Guided tour Dachau

We have used BigHatTours - he was fantastic.

We are returning in Dec w/10 friends and he was booked, so we are using Tours By Locals.

We also did Third Reich & Documentation Center in Munich enroute to Dachau w/the above 2 tours. Excellent also and I think needed for all inclusiveness of the Nazi era.

Many years ago, we used Radius Tours - recommended in the Rick Steves book and it was 'ONLY OK'

Dark History tours would be my recommendation. Taff spends considerable time with this subject and has given tours to both liberators and survivors as well as in-depth interviews with them, so he has a lot of first hand information. Since I am a tour guide that spends a lot of time talking about this same subject but in a different area, I really appreciated the huge extent of his knowledge about Dachau. The entire train trip there and back was spent with him relating information to me and my husband.
https://darkhistorytours.com/

If Dark History Tours also makes a detour to the NS Documentation Center in Munich on the same day and also tells you a bit about the buildings next to it, I would definitely do that in addition to Dachau. For me this context is always important.