they both have pros and cons...
maryland live because its attached to the mall, thats where it ends. its so spread out.. i have no idea why whoever planned it didn't make it less from door to door and just add another level.
horseshoe has good restaurants and the layout is better. plus they are a part of total rewards, so you can use your comps towards an atlantic city trip. personally i would wait for a good football game and just do both in a day. maybe the third preseason game. ravens vs redskins.