[mimischi]

For clarification, “default” above doesn’t mean “In Berlin you get insured with TK by default”, and rather “Most people in Berlin will recommend choosing TK over a different state-mandated insurer”. TK was also very popular when I was back in university in Frankfurt. It might just still be the one with reasonable prices!

[mejutoco]

IIRC you can move from TK to others freely, but if you move to some options there are conditions to come back.

TK service via email, phone, etc is amazing, even if your German is not very good, as it was the case for me the first year.