I have used Amazon HD through WiFi on a Bluesound Node 2i and an Auralic Aries G1 for a couple years now and have been completely satisfied with the sound quality and their vast catalog. I can't comment on Qobuz as I have not compared the two.
I occasionally stream through Airplay but find the sound to be improved streaming directly to the devises through WiFI using the devise apps and not the Amazon app. The Amazon app is fine and actually better than the Bluesound app but you are limited to Airplay. I believe Airplay is limited to 24/48 Res where through WiFi you get the full 24/192 resolution. Also, I find the Auralic Lightning DS app superior to the Bluesound app and it interfaces to Amazon HD perfectly.