I support living artists, so whatever format they're selling at a show or in a record store, that's the one I'll buy. I stream as well but often use that to decide what to buy (and who to support).
Quality wise, CD usually but I like LP artwork, the ritual of playing vinyl and reading the occasional liner note.
FWIW, this discussion is similar to many I have in the photo world (I'm a fine art photog). Digital vs Analog. At the end of the day, they're just different experiences.