I don't think so. I assume that they're equally popular, UNLESS one of the parks has a recently opened attraction. For example, at the moment, it's possible that DisneySea is the most popular of the two because of the newly opened Finding Nemo / Dory ride. The number of ride closures could also impact where the crowds go, but as the crowd is pretty much ALL locals, those kind of issues wouldn't necessarily be a determining factor for them (since they can go so often).