If you're looking for a coffee shop on the square, Colectivo is your best option. I'd say their biggest strength is actually the quality and variety of their coffee and espresso, which is surprising as you might think a place like this would simply thrive by being so close to the capital. They have a new espresso type week, which they mostly source from Central or South America. They also serve a variety of food items that are small enough to be quick but large enough to be satisfying. I often choose colectivo for a quicker brunch on the weekends over other sit-down restaurants in the area.
Wifi is free but starts late-morning / early-afternoon on the weekends.