I still think that CDs are the best physical medium that we have. They're tough and not susceptible to physical imperfections like LPs; they're small enough to be portable, but large enough to have cover graphics (the canvas is small but ones with larger booklets are cool); they're cheap to make so that they're a very democratic medium (which means that they're cheaper to sell so that they can get in the hands of more folks) and finally, the sound quality is very good, even if some folks will argue that it's not as good as vinyl. On that last point, I would say that in some respects it's actually better than vinyl: you don't need as expensive, perfectly calibrated and maintained gear to realize good sound quality, the bass can be stronger and you don't have to deal with lots of things that ruin the sound quality of LPs like poor pressings or poor condition. That last aspect makes CDs a great bet for buying used because in the vast majority of the time if a CD doesn't look to be scratched, it'll play perfectly.
All that being said, whenever possible, I prefer to buy a clean copy of an LP rather than a CD. This is really just my collector's mentality taking over though and isn't a choice that's made from any kind of more practical consideration. All in all, streaming music really seems to be the most practical model as it's clearly the best value and the sound quality can be quite good I'd imagine if it's CD or better quality. Still, what a bout a physical copy of something that's going to be for sale at a band's merch table? Unless the artist has a lot of money to dump into a run of LPs, and even then they might not be selling all that well as less folks own the gear to play them or want to spend $25-30, than a much cheaper to produce and cheaper to sell (with even more % profit too) CD seems like a perfect option...
