I have Spotify Premium. I like it; it's fast, its catalog is huge, and it's a great place to discover new music. However, in today's digital world, there has been a resurgence in the tangible, physical media that came before Spotify and Apple Music. Nowadays, you can find vinyl records, tapes, and CDs for sale at all sorts of places. To me, CDs stand out especially due to their easily archivable nature (e.g. throwing them on an iPod Classic) but also their impressive audio fidelity. They sound great!
I have a shelf of CDs that I use in my Technics 5 disc changer (SL-PD887) and my 2009 Honda Accord. They're very compact compared to vinyl, while also making a lot more practical sense than tapes. Granted, each of these formats is unique and deserves a place in your tower of power. However, if you too are tight on money, CDs have one final trick up their sleeve: They're cheap. Seldom will you buy a new CD for more than $20, excluding box sets and rare releases.
So, if you're interested in building up a physical music collection, don't forget about the humble CD. It may not have the character of tape and vinyl, but it is the workhorse of audio. I love my 70s Pioneer turntable, and I have more Depeche Mode tapes than I know what to do with, but I can guarantee you that I'll keep using CDs just as much as those formats (if not more) for as long as I can.