This is a very broad topic, and I have yet live in three major cities (Berlin, Cologne, Munich), so I'll cover those, and please feel free to file a PR if you feel you know well of other cities 🙂
To warn you upfront, all major cities have housing issues, but as foreigners it's still better to be in these cities due to the infrastructure, the amount of people speaking English while you're surviving with your basic German skills.
Berlin is a very diverse city. Language, nationality, religion, gender and sexual orientation, whatever you can name, you can meet new people which you wouldn't have met when you come from a very homogeneous socity like where I'm from. It's very difficult to Berlin describe in words or sentences, but I think the netflix series Unorthodox shows what Berlin is like. In 2015, 20% of the inhabitants were foreigners and I can imagine that it should have increased steadily except during pandemic.
You'll not find that difficult to find a community of your cultural background. Restaurants, supermarkets for specific countries you can find them everywhere and you can try out new stuff if you're willing to, thus if you think you might feel homesick one day, Berlin might be the best place you can be, because for whatever reason you might left your own country for, you can't fully escape from your cultural background and might need some occasional cure to get away with it.
Inherent to its diverse nature, you can perceive Berlin as more accepting/open towards foreigners and different culture. Due to this reason, if you want an English speaking tech jobs, the most jobs should be in Berlin. The jobs leans more towards startups and smaller companies, I don't know the exact policy but I think legislatively, it is more startup friendly.
Housing is a big issue in Berlin, the rent has increased a crazy amount due to its high demand as it's a popular city for foreigners but also accepting refugees made the housing situation more difficult. It was not that expensive city, like ten years ago I heard, but the living cost is not that cheap anymore.
And sad to say, but Berlin is the city that I've experienced most explicit/violent racism, including micro aggressions. I think it might also relate to having more diverse people, but from getting weird comments to showing to threat with gestures I've experienced them all. I might consider myself of being lucky to haven't actually been hit, but I know people of colors who had suffered from extreme violence as well.
Compare to Munich, I feel its bit more unsanitized, if you like a clean city like some East Asian city does, you might not be very happy about it, but not all places are like this. I feel this will be less likely if you get away from the center.
TBD
I feel Munich is a city for settled families. There's not much interesting things going on day to day, but there are great nature around the city and in the vincity if you like hiking or skiiing, this might be a place for you.
Other than that the living expense is one of the highest in Germany, rent for an apartment living varies, but I you'd have to pay minimum 1000-1200 EUR if you want to have a decent place for yourself.
I've lived for more than two years, but I haven't faced any explicit racism that I was aware of, maybe because I'm living in an area where it is more for families and less busy, but the popular density is much less than Berlin in general, so you just meet less people.
In terms of sanity, I feel Munich is clean in general, even inside the S-Bahns are clean and very well maintained.
Compared to Berlin, Munich has more conventional companies such as manufacturers and well-known big German companies. Also many big international companies has their offices here.