Stayed in Hostel Elf in Prague for 3 nights on my way home from my Erasmus. I was in a 6-bed dormitory.
Showers were clean, there was hot water at any time of the day, water flow was just like home.
The bedroom was very clean, bed was comfortable, the curtains actually block the sunlight.
All staff spoke perfect English and were very nice and helpful.
There were animations during some evenings (movie night, free sausages, happy hours....) that allow you to meet the other travellers.
Best part is the FREE BUFFET BREAKFAST every morning. You can also have a FREE tea/coffee at any time of the day or night.
Wi-Fi worked perfectly.
It's very close to the city center (15 min by foot, I didn't use the public transport).
For the price you'll pay it's honestly the BEST accomodation you'll find in Prague.