If 28mm is your thing, then the Q is better than the M (and the same price as the new 28mm Summilux, alone) because you have the option of autofocus and other modern mod cons which will get you more reliable results, depending on what you are shooting.
If you need to use a wider range of focal lengths, then it's the M or Fuji or perhaps even Sony, although the lenses are getting bigger as we go along.