I've read and enjoyed both, a lomg time ago (I ought to reread them). I voted for "The Left Hand", which I fear was probably the wrong answer. Of course, they are different animals, since the first is really fantasy (with some SF trappings) and the other is quite "hard" SF.

What I liked about "The Dispossessed" was that initially it seemed that we were being presented with a straight contrast between a Utopia and a Dystopia, and it only gradually became apparent that it was far more complex than that. In fact for a while Le Guin had me fooled into thinking that she actually approved of her "Utopia" and that she might actually see its faults as virtues.