Well, it's all subjective, isn't it? I've had the Arya Stealth for a couple of months and it's become my favorite headphone (and not by a small margin) even over my ZMF Aeolus. Imaging, separation and stage, in particular, are just wonderful. However, my one criticism of the Arya is that I find it bass light compared to the Aeolus and several of my other headphones. Now that is quantity only--I think the bass quality of the Arya is the best I've heard. When bass is prominent on a track (I'm a sucker for bass guitar and that's mostly what I am talking about when I am talking about bass), the texture of the bass on the Arya is just incredible. However, when a track gets busy and the bass is not placed particularly high in the mix, bass lines that you can still follow on the Aeolus are often hard to pick out, or almost totally lost, on the Arya. (I don't listen to EDM. modern pop, or hip hop which I believe tend to have more sub bass than the music I generally listen to. Since the Arya's bass extends deeper than the Aeolus, bass in those genres may fare better. I am talking abut mid bass where the bass guitar primarily lives.)
I should note that this is only addressing sound quality--by far the most important issue. However, while I have been pleasantly surprised to find the build quality of the Arya Stealth to be more robust and premium (or at least not as non-premium other than the current shoebox packaging) as most reviewers do, and it is supremely comfortable, it simply can't compete with the special feeling you get when you put an Aeolus, like any ZMF, on your head since every surface you see or touch is aluminum, real leather, or gorgeously finished wood.