The glass on the 6-24x50 PST is fantastic. I've heard that the 4-16x50 can be hit and miss, and the 2.5-10x44 is the red-headed step child in the family.
I recently had to decide between the PST, Sightron SIII, or a used Mark4. It really just depends on which power range and features you want. The PST comes in FFP, and the SIII doesn't, I don't believe the Mk4 does, either. A zero stop and illum. reticle are other nice features of the PST. Some people like the glass in the PST better than the SIII, but most reviews show the SIII having just a slight edge in optical quality over the other two scopes. Tracking in all 3 is superb. Hard to go wrong between the 3, but you have to pick the scope that has the most features that you're looking for.
The SIII is a great target scope, and the PST is a better choice for tactical-style shooting. The Mk4 is also great, but I wanted FFP in this particular scope purchase.
For hunting and target shooting, I went PST. No regrets.