I am not the kind of person that will bash or put down my competition so I am going to be limited in what I say on some fronts.
The Z2 is faster out of the box and on gun from our tests (drop tests are the biggest bunch of crap to measure loader performance), it is also far lighter, a lower profile, and doesn't have issues with cheap paint, swollen paint, or dirt getting into it through the speed feed. The auto unjam system works so well most people don't know it even activated. That allows it to work with reballs, and crappier paint and in conditions that other loaders won't feed under.
The Z2 also has a full range of adjustability if that is of use to you.
The Z2 has a 33% larger lid opening for easier reloads and a quick load lid system that opens to still allow you to load from a bag of paint or easily empty your loader if there is a broken ball loaded, or at the end of the day.
The Rotor is simpler to take apart and reassemble, but the Z2 is much improved over the original prophecy on that aspect too.