Personally i enjoy fighting the same clans. It allows members to get grudge matches going, and gives them a heightened perception of the clans true strengths. If you war the same clans over and over again, itm ost certainly means you are of roughly equal capabilities, thus delving into the abyss of the unknown when you make a declaration, or accept. I believe that this is also one of the best ways to bring out the true potential of your clan, as you find members caring more about the outcome.