Went with 3 people this season, all different times, and two thought Pandora was the best. I think the bright UV lighting is the main appeal, since it’s easy to see and walk through the actual maze without the fear of running into walls and falling down. UV lighting is also not commonly seen by general audiences, so it has a special, slightly magical, feel to it. The maze also isn't IP, which stopped some people I went with from enjoying mazes like US or House Of 1000 Corpses.
The success of Pandora leads me to believe that HHN will have a cut budget next year, as originals are now doing as well as IPs. I don't expect it to majorly affect the event, but we could be seeing a 50/50 split of originals to IPs in the near future. If they don't cut budgets, Potter is definitely a consideration. Consensus is they didn't open the area due to the fact wands are seen as weapons, and the land makes the majority of its money through the purchase of them. We were supposed to get full potter open on sundays, with death eaters who were already costumed and apparently payed. There also is talk that there was to be a small walkthrough open with the land, although I can't seem to remember if the rumor had any true backing.