I save every quality piece of Shadow art I come across. I've been doing this for years.

Sonadow - 6,383 Files - 2.73 GB
Shadamy - 1,269 Files - 646 MB
Shadouge - 1,669 Files - 859 MB
Shadria - 6,525 Files - 3.64 GB (Around half of this is truly shipping art. And unlike other ships, Shadria is mostly posted on sites like Weibo/Pixiv/Lofter, which compress files less).
Knuxadow - 318 Files
Shadikal - 117 Files

I consider Shadouge, Sonadow, Shadamy, and Shadria to be the 'big 4' when it comes to Shadow ships. The other ships for him are mostly irrelevant outside of porn maybe.