special achievement for tough lads / lassies is to move to dodgy eastern countries like czech republic, croatia, romania to save on tax. forget about doing the grown up stuff in english there and when your child gets sick or needs education you need to fly right back to daddy germany.
portugal and ireland also have tax incentives but I dont think the quality of life, services or health care are comparable to germany.
all in all since brexit, interesting and realistic solution seems to be switzerland, but it has its own quirks.
in my opinion you would do better to stay in Germany but move to a more sensible location than Berlin. Get a piece of land where still possible. Germany is a safe bet and will be last one to crumble of the EU states, on paper...