In lieu of some responses, I would like to elaborate further on what I had stated; some manufacturers design their gear in manner whereby it will benefit one over the other, although they offer both RCA and XLR; therefore it isn't that the cable (type) is better but rather it is a better match for the design.
One person above mentioned Meridian, due to their design, they will tell you that XLR should give you best results with their gear.
One person above mentioned Meridian, due to their design, they will tell you that XLR should give you best results with their gear.