Very much horses for courses IMO.
I prefer the Panoptic ... until I've looked through the Nagler. Then I prefer it until I view through the Panoptic....
You get the idea.
The only real difference that I can see is a slightly flatter field with the Panoptic - in faster (f7 and below) scopes
In a slower scope, (f8+) I would choose the Nagler. For my f15 Mak, I wish they made a 50mm Nagler!
Neither of these EPs will disappoint and the Panoptic is in no way a "poor man's Nagler".
Now there's always the 48mm Brandon....