I personally download actual mp3 files from Amazon (not amazon "music" but just purchase actual tracks). In fact, I continue to be pleasantly surprised that in 2018 one of the big providers is doing something as simple and friendly as this: selling me unprotected, plain old mp3 files.
However, they are compressed mp3 files and not suitable for future transformation so if there is an album that I want, I will still purchase the actual CD and rip it to the full WAV/PCM.
My system is a mac pro (2009) which still has an optical drive. I use the (excellent) 'abcde'[1] tool to rip the CDs. I particularly like the fact that it pops up a 'vi' session with the gracenote/cddb/metadata so I can quickly "fix" the usually braindead cddb entry right in the workflow.