Ventana Sur is the best hostel you can find in Santiago, if not all Chile, period. We already stayed there for almost three weeks in 2015 and were happy to return once more. It's well located in safe Providencia neighborhood, has great breakfast, parking - but most importantly, it's owner Ivan.
I believe he's the one that makes the hostel special - he will talk, help, cook, drink, help you some more all the time. All the thank-you writings all over the wall in the garden prove that.
There's a reason this hostel had the best review in Santiago. If you're looking for a place, look no more. This is it :)