I also highly recommend Pine Hill.
Here's their Home Page.
Pine Hill was the very first RV park we ever stayed in and we have returned many times. It's actually located in Krumsville, north of Kutztown, which is Exit 40 of I-78. Most sites are pull-thrus.
The only negative comment I can make is the electric and that is not the CGs fault but the power company. Being there in April/May shouldn't be a issue but during the summer when everyone is running their A/C you'll find the voltage low. By low I'm talking 108 volts or less. It was at Pine Hill when I bought my first AutoFormer.
There are other parks in the same area such as the KOA mentioned above and another is Robin Hill that's also nice but a bit of a hilly area.
DO NOT even consider Kutztown Campgrounds such as New/Old Dutch Mill Campground or Sacony Park Campground. These 2 CG's will make the worst CG you have ever been in look desirable.