What are the top 3 natural park type places in Spain?

Just remember that, even in the Barcelona area, January can be very cold. So 'somthing pretty and green with waterfalls' may not work out. Natural areas also tend to be in the mountains where there is bound to be snow. A good day trip from Barcelona is to Montserrat. While this is a pilgrimage centre, there are also fantastic bushwalking trails in a natural environment, beautiful views, and rugged mountains. It's only about a 45 min trip out of Barcelona by train then either rack railway or cable-car. A wonderful place to visit and I highly recommend it, but not sure about winter! http://www.montserratvisita.com/change_language/_Uj6lvoXZdP6g8E8ttzvAXJu7kmckmRtkwU1N3p4nl6DVdfzPBZM7Xw

For natural places, near Barcelona I recomend you, Banyoles (lake, 1 hour) and Montseny (green, 1 hour). Aigües tortes i l'estany de sant maurici is very far for a day, more than four hours driving, and is very extensive, is for a weekend (minimum), whatever in january is snow.

The Only National Park in Catalonia is Parc Nacional D'Aiegstortes I Estany de Sant in the Pyrennes Mountains. It's a 4 1/4 hour drive from Barcelona -- a little far for a day trip. The Parc Natural de la Zona Volcanica de la Garrotxa is about 2 hours from Barcelona Ordesa National Park is 4 1/2 hours from Barcelona, has the waterfall known as Cola de Caballo (the horse’s tail). I can't say if these are in the top three -- Picos De Europa was the one I liked best, but way too far for a day trip. As all these places are in the Mountains, you may not be seeing a lot of Green, most likely you will have snow in January. Only pine trees will be Green. Also, waterfalls don't run in winter like they do in late spring early summer.

I'm sure you'll find something pretty and green. There's plenty of that not far from the city limits of Barcelona. Mountains and all, mean lots of waterfalls. ¡Buen Viaje!

There are many Parques Nacionales in Spain. I have been to several and I am fortunate to live just 5 kilometres from one of them. However, if you want the best, then you must go to the Parque Nacional de los Picos de Europa. It is not only the best in Spain, but one of the finest in the whole of Europe.