At the moment CLE does have more but this past summer for several months CVG had a few more when I looked. CVG may be cheaper to operate out of considering is more centrally located in the country therefore having shorter legs and may decrease the need for company paid hotels. Also, I would imagine a much lesser frequency of de-icing in the winter at CVG. The company probably doesn't care but if you had to commute to one or the other, CVG would likely be easier given the high volume of freight.