The Nürnberg zones
The VGN has the benefit of being yuge at least.
I think Brandenburg's is the whole state + Berlin. So that's even better.
Not like the Deutschlandticket has any real future unfortunately. Gotta see if it at least survives the Merz government.
As for DB - the ICE are horrible when it comes to reliability, but I found the regional trains actually mostly pretty good. Even if they have the tendency to be kinda dirty and always have broken toilets.