You have a flight at 6am in the morning (say, to Santorini? 🙂 ) and you don’t want to stress missing the flight. Stay here.
It’s nothing exceptional but it’s a 2 minute walk from the hotel door to the airport. It’s comfortable, proper bathroom amenities, and you will get a good night’s sleep.
We weren’t overly impressed with the food in the restaurant on the ground floor, I recommend you grab a gyros from downtown Athens before catching the metro from Syntagma station which gets you right to the airport stop 🙂