Sonos, Apple TV or something else?

Hello,

I'm currently streaming Spotify from my Mac via Airfoil to my Airport Express into my Supernait via optical. Wow, bit of a mouthful! 

I'm looking to get Spotify directly into my Supenait with a wired connection and happy to control via an iPhone app. 

I'm thinking of going for the Sonos (heard it's better than Airport Express for clocking reasons on wireless) but just realised I could also look at Apple TV and connect directly to the Supernait via optical, and control Spotify by the iPhone app. 

Would this be as good as the Sonos? I have heard all user interfaces are generally good, but I'm after the best sound quality and reliability. I don't store files on a drive or anything, I almost always stream from Spotify and sometime use iTunes. 

Am I missing out on other devices like the Cambridge Sonata or Squeezbox, or if I'm using the Supernait DAC, does it not make any difference which I go for, as it's merely acting as a router for the streamed music?

Thanks!