Extensive experience w both storied firms with well deserved reputation for excellent engineering, sonics, support and typically some level of upgrade path without scrapping / selling the whole box. As others have stated, they each have strength, in image depth and air, i would give nod to ARC, bass drive, nuance to Aesthetix. In my system the ARC Ref5se is also quieter and more detailed. I do have an Aesthetix Pandora Sig feeding the ARC. At the level you are at tube rolling and isolation will both improve image depth, I use HRS, but there are other brands that yield similar results. Best wishes in your journey.
Jim