Been to both - CDS in Disney; BMG in Chicago.
IMO (and I'm a drummer), for overall entertainment value, the edge goes to CDS. Cat 2 tickets can been had at great discounts and are great seats.
However, I absolutely loved BMG and would see it again before I pop for CDS.
Life is short - plan on seeing them both; maybe not all in one trip, but certainly before you're too old to truly enjoy.