I'd say readability is more important, unless you know a given piece of code is going to be a hotspot, in which case optimizing it for runtime would be more important (with proper documentation to describe the optimization if it is non-obvious).

What I like in Python is that, once you are at easy with it, and that doesn't take too long, readability correlates many times with code succintness. Paraphrasing Eistein, "make it as short as possible, but not shorter"...