The PA EZPass has a $3 annual fee per transponder and a higher replenishment amount.
If your trip is a week or more out, assuming you're located in Illinois as your profile says, consider getting an Illinois EZPass/IPass. It has no fee, the deposit is refundable, and the replenishments are lower. Plus PA toll roads give EZPass discounts to all EZPasses, not just PA ones.

As for the person that said NY, out of state residents will receive a Port Authority (PANYNJ) EZPass which has a $1 monthly fee. Other NY issuers (MTA and Thruway) don't charge the fee but your mailing address has to be in their service area.

Wiki article that compiles all EZ pass information by state