More important is where you place them. Try and not crowd them together, or squabbles will occur. For the safety of the birds, place them in an area away from neighborhood cats, or at least make them as inaccessible as possible. Keeping the area around the feeders raked up from falling seed will also help keep the birds up on the feeders and not on the ground where they can become attractive targets for cats and the occasional bird chasing dog. Be warned though, that this does not always work.
People have different opinion as to the colors used in feeders and houses.
Some say bright colors need to be avoided, but one of my most visited feeders is bright yellow. Keep color in mind though if you find a feeder used more or less than another one. A last word on feeders that many people do not consider. Keep them clean. Birds will avoid feeders that have accumulated seed that has molded or soured.