I would recommend the PSR-500. The Pro-96 is an older model. The PSR-500 will do 700 MHz trunking (you'll need that in a few years). The Pro-96 does not. PSR-500 has Mil-Air out of the box, the Pro-96 has to be activated via software.
The PSR-500 comes with programming cable and AC Adapter. The Pro-96 does not.
I have the PSR500 and the BCD396T. The 396 rarely gets used anymore. I really love the PSR-500. It has sooooo many features that the 96, and 396 does not.
PSR-500 has about 36,000 channels (21 V-Folders w/ 1800 channels each)
Pro-96 has 5500 channels (11 V-Folders w/500 channels each.)
Just my opinion.