@cigoL it depends a bit on your needs.
If you would like to use Renoise exclusively (no other software, hardware or midi controller to connect) for fun, you can use Pulse Audio. Not the best performance but ok and also no hassle.
If you have a midi controller, i would suggest pure Alsa (this will mean that you can have only one application use audio at a time) and audio realtime priority settings for the kernel. You don’t need Jack for realtime audio priority. Great performance and very stable, setup once and be good, not very flexible.
You will definitely need Jack if you want to connect a lot of audio stuff (software/hardware/midi) with each other or if you would like to use a application that has Jack as a dependency.
If you seriously want to setup a dedicated audio production box to use in a studio with a lot of other stuff, than use Jack, audio realtime kernel priority, a lightweight desktop (or only a window manager), ethernet (no wifi/wlan) and disable all services that are not needed to get the max for audio. The system should also have a good dedicated graphics card (a good, not a high end gaming sli double) to render the UI, so the CPU doesn’t need to do that.
BTT: I guess you need to connect the Bluetooth speakers in Jack, Spotify and Youtube use Pulse Audio by default if not configured otherwise. If Spotify and Youtube can play back at the same time, you definitely use Pulse Audio. Audio production over Bluethooth is really a bad idea, too much latency and overall interruptions.