I recommend the Samuel and Vanessa's place for a host. And that's because:
1. Interesting authentic barrio. Close to reach the center on feet. For a sightseeing, really economy on metro. And the barrio itself is very nice. Near many bars and restaurants, also the shop works 24hours
2. The room is simple, but includes all what is needed. Table, the nightstand, shelves, big wardrobe. The balcony. All is very comfortable.
3. Samuel and Vanessa are nice people, always can help you and fast reply. They can speak English.
If I be next time in Madrid, I d like to stay in the same place. Muchas gracias.