I run a VX-5HD on my 7mm Rem Mag and highly recommend it. Performance wise, both should be more than adequate as far as light transmission, clarity and accuracy are concerned, so I would dig more into the features that will/won't work for your applicaiton.
The Leupold will be significantly lighter weight (~19 oz vs ~28 oz). In my opinion the simplicity and accuracy of the CDS custom dial is extremely difficult to beat for a hunting rifle. The zero lock on it is excellent too. Downside of the CDS is that you would have to get multiple dials made if you plan on shooting more than 1 cartridge, or just use the original dial without specific yardage marks for the less used cartridge. This was non factor for me as I only shoot 1 cartridge for whitetail to elk.
The Vortex has FFP if you're big on that. The big positive of FFP is using the reticle for hold-off at various magnifications and not having to dial (always accurate reticle holdoff vs SFP is only accurate at a designated magnification). I have yet to find this to be applicable in hunting situations. The "tactical" reticle and more dialing features would be nice though if you plan on using it on a dual purpose hunting and long range target rifle.
The bottom line for me is that the VX-5HD is designed to be a hunting scope giving it a far better set of features for that purpose than the VIPER PST II, which was designed as a long range/tactical shooting scope. Both are very good scopes though.
If you want a better Vortex option for hunting that is comparable to the VX-5HD and roughly the same price point, I would look at the Razor HD LHT.