The good news is that you really can't go wrong with either. Both are top shelf choices. I have a GZ pro and a DP prem sitting side by side. I think GZ is slightly the better game overall; shots, rules, lightshow etc. but as weird as it sounds, I think DP is just a little more "fun". I think it's the quality of callouts, the awesome music and just overall goofiness that pushes it ahead.

I would say, get a DP now as they will be going out of production well before GZ. If you like it, keep it and pick up a GZ next year.