Amazon (on Windows, anyway)
- Works only through default sound drivers
- Hard or impossible to get through a Roon or DLNA system
- Very large catalog
- Low cost
Qobuz
- Works through ASIO or WASAPI Exclusive sound drivers, which gives best sound
- Networks easily with Roon or other systems
- Smaller catalog than Amazon
- Slightly higher cost
I did not make sound comparisons. Qobuz won for me because of its ability to integrate with my main (networked) audio system, currently using Roon, previously using DLNA. It also was a winner by independently controlling the sound drivers used, to avoid meddling by Windows or other OS in my desktop (USB-connected) system.
I found Amazon HD an exercise in frustration to get working at reliable highest resolutions or to integrate with my system. Perhaps that has changed in the several years since I tried it?