Mandarin still the best but as noted basic of basic rooms is quite small - OK for one. Is it worth the [substantial] extra cost? Not entirely clear cut, but if you want the best it is the MO.

Charles is distinctly average IMO, its fine. Bayerischer Hof and Vier similar and not, Vier similar location to MO. Between the three go with location thats useful. Vier seems the better of the three but haven't been there in a while.

Rosewood will open later this year/next which will be the place to be.

If you want fun off the beaten track, stay at Roomers Munich and get a big room. Certainly not the choice if like old school/true 5* luxury. More like high end W and can have a scene. But based on "quieter location" I expect not!