Often I prefer to work in silence, but I also have several playlists to listen to while I paint or assemble, usually OSTs, from either movies or videogames: Conan the barbarian, Plannescape Torment, Elder Scrolls (usualy Morrowind) Journey...
Rogue Hobbies have a video of tunes of her own making with a 16-.bit jrpg vibe which I also find perfect for that.
More "energic" sounds like Power Metal are usually reserved for driving or house chores, but whenever I really need to lift mty spirit for painting I usually go with classics like Rhapsody or Nocturnal Rites, although sometimes I use that time to try some new band.