I do both - purchase music that I want to keep (usually on Bandcamp or CD) and stream otherwise. It means I support the artists, I don't have to worry about network/regional/copyright availability when listening to my favourites, but I also don't miss out on high-quality audio in cases where storage is an issue, streaming exclusives, or long shipping delays when ordering albums on CD.

For streaming, I use Tidal, as it is the highest-paying option to artists available to me while also being lossless (or close enough in case of MQA). I tried a few others but found no real benefit to switching. I wish I had access to Qobuz though.