I like to listen to music that shares the same vibe as the project I'm working on, so it depends on what I'm doing. Ambient music with no lyrics/voices is perfect when I need to focus (like when writing). I started listening to Dungeon Synth, Ambient and Dark Ambient music recently. Perfect for when I need to focus and relax ^^ Here are some of my favorite pieces so far :
Asleep and well hidden by Kammarheit
Stormens ryttare by Ornatorpet
Mineral Hall by Louie Zong
Gently veiled by Silent Cabin