Abest Cube was mad decent, clean and well-kept facility with quiet rooms (due to their own policies, which are similar to a capsule hotel). Although it's right on Kokusai-doori it's relatively chill. Moreover, the lounge is spacious and comfortable to hang out or work in, and the included drinks on offer were a nice touch. Staff was friendly, the guy who checked me in was Nepalese and I think the other two guys I saw were Japanese, but communication was not a problem.
Haven't stayed at MyPlace yet, but it has a more relaxed island hostel vibe. They also offer diving packages, so I'm excited to get back in the water when I return to Naha.