We'd recommend Marianna and Pavlos to anyone who asked us for a recommendation in Thessaloniki.
Fantastic location, super-speedy responses, very accommodating, we couldn't ask for anything more. In fact, when our flight out of Thessaloniki was cancelled and we had to stay two extra nights, we didn't even bother looking for a hotel or another AirBnB, we contacted them immediately because we knew we'd be comfortable there.
One note: others have mentioned that there's a DJ nearby that plays music somewhat loudly. We stayed on many nights, including Friday and Saturday, and it always stopped by 10h at the latest.