Well a lot of what I like I can just download from qobuz or spotify. Lots of other stuff I can find on nicotine. What’s most difficult though, is obscure artists in the electronic, experimental and art music genres. For example one of my tests for how thorough a catalog is is by searching for classical composers Taneyev and Arensky, or the electronic artist Forss (who coincidentally founded soundcloud). I especially like to look for lossless audio like flac