We enjoyed the Ostello degli Elefanti. We were arriving late so wanted a place we could check in at any time. The staff was helpful and always present. And the rooftop bar was low key with a lovely breeze and view. Have an Amaro di Etna!
Do note that the hostel is in a very active central area! There were musicians (on street and in nearby bars) playing until quite late. We cooked dinner in the shared kitchen which was fun!