I love the impression of diversity in the plants of the first image. The lushness is also a big plus.
I like the look and feel of the rocky one too, almost better. But it lacks a little. Namely a greater diversity of stone and sand. I almost feel like with a little more work the second image could be better than the first.
One problem here, and in a number of other renders posted recently (by lots of people), is a real lack of displacement and texture work on hard surface objects. But even if its just a test for placement, its almost better not to include buildings and such, because they can really make an image look fake.
On the other hand, I know "photo realism" is not everyones goal (nor should it be). Often some of the renders I like best are illustrative or stylized, or cartoony. But then it should be one or the other. The aesthetic of real and drawn in the same image, really conflicts and makes both look bad... more thinking out load than critiquing. Just some thoughts that came to mind.
