I think that Palazzo Parigi has by far the best rooms and suites in Milan, but because it is owned and run by the architect who designed it, Paola Giambelli, food and service tend to take a back seat. I would still go back there, though, as it is a beautiful hotel.
For service and food, FS cannot be beaten. If you choose one of the refurbished Pierre Yves Rochon designed suites, the experience is even better.
MO does not work for me, either, except the summer courtyard, which I really like.