When I organised battles I'd often have beats and acapella then you had the best of both world's. They are different skills, I probably like beats best cause the shyt also had to flow and sound good, acapella lets a lot of trash motherfukkers get away with some bullshyt that ain't really rapping, I've seen some really awful shyt under the guise of acapella. Both have their advantages and disadvantages though, but I think both is a good test of skills.