I used a mix of Cycles with Corona because in some renders Cycles did better a better job the foliage than Corona, and sometimes Corona beat Cycles.
Corona was mainly used for the buildings and furniture, but for every image I rendered on both Cycles and Corona and picked the best bits of both.
The trees were created using the Blender add-on The Grove. Absolutely amazing add-on! Trees are so much fun to make and so easy to experiment with, for example having 2 trees compete for light against each other.