My vote would go to Pizzafari. I really enjoy this location compared to the noisy and kid-packed Pizza Planet.
If you HAVE kids, they will probably enjoy the atmosphere at Pizza Planet over at DHS much more. Just be prepared to spend more money, not on the food, but on all the various arcade games and toy dispensers. Your kids WILL want to play these!
If you DO NOT have kids, you will probably enjoy Pizzafari more as it is quieter and more relaxed. It also has some wonderful painted murals on the walls of the various dining areas..be sure to visit all the rooms to check them out!
As far as the food goes, it is about the same to me. I prefer Pizzafari, and last time i had pizza there was about 5 years ago, and it was not all that bad. Their 'Breakfast Pizza' i tried for the first time last week, and it actually was quite yummy and unique. Worth a try if you are up for trying new things and experimenting.