When I'm really in the mood to listen to Power Metal/prog metal, I have a very specific desire to hear just that.
In other words, I'm more concerned that the bands come across powerful, energetic, and most of all, epic. But not so over-the-top that it becomes a complete parody of itself.So, exciting tension building verse with really big, resolving choruses with strong inspired melodies and guitarwork.
A problem some bands find in the quest to be "epic" or "progressive" is that they forget to establish the framework of just being plain awesome in pursuit of technicality or sheer speed. Not to say innovation is bad. It's great. But I think that it should still keep its identity.
TL;DR Power Metal should be just that. Powerful.
My favorite power metal album:
Seriously. This album fucking destroys.