Only having experience with HDtracks, they don't really have much. Sure they have the most popular stuff for the most part but I often find that albums are missing for an artist or entire artists are missing. Not sure if it is a geographic restriction or if its like that everywhere.
Bandcamp really is a treasure trove for finding releases of established and new independent artists. It seems that their business model is quite fair towards artists as well. It also seems that their acquisition by Epic games hasn't negatively affected them so far.
[Edit]: And they offer all downloads I've encountered so far in several lossy and lossless formats, including FLAC and WAV