I stayed in a 24-bed dorm at Hola Hostal Eixample.
The check-in procedure was great, even though I arrived at midnight. You can rent a towel for €3, and linen is provided for free. There's a locker with an electronic access card that's beside each bed. It's big enough to fit a 40 L rucksack easily, plus some more stuff. Showers were clean and spacious as well. I didn't use the kitchen much, but it seemed fairly well organised. It's located near Tetuan station and can also be easily accessed by night buses.
One negative: because there were 24 people in one room, it was very hot and stuffy at night, despite the windows being left open.