Haruka W.
Yelp
My favorite place to study in Prague, hands down. The entire place is lined with glass windows, which means there's enough natural lighting for you to spend hours studying without feeling too cooped up. The staff are all very friendly, there's reliable free wifi, and the coffee and treats don't disappoint either--what more could you ask for? There are also a few tables outside (and the wifi reaches outside!) for warmer, sunnier days.
The only downside might be how popular it is among both local students and students from abroad, causing for a bit of competition over seating on busy days. But, I mean, it's hardly their fault for being popular, and I can't blame the place for their customers.