I've stayed at both the Munich Marriott and the Renaissance. I really like the Renaissance for the service and the breakfast, but it was previously a Ramada, and the rooms (at least some of them) do show the wear.

At the Mariott (two blocks down from the Renaissance), I was upgraded to a nice top-floor suite of rather unusual proportions (rooms not rectangular . . . except, of course, the bathroom) nicely appointed, great view. The bar area is a bit nicer, large TVs. Breakfast about the same as at the Renaissance.

Both places, staff were wonderful.

On the whole, I tend to stay at the Renaissance, but either is nice.