SF antho with a twist

I'm ambivalent about theme anthologies. They can be great -- but limited to a specific topic, all too often an antho's stories, however excellent individually, begin to blur. 

Looking for a great SF antho?
Check these outNot so the Shapers of Worlds anthologies, edited by Edward Willett, of which I recently finished reading the third-and latest volume in the series. How does Ed consistently dodge the too-much-of-a-good-but-same-thing bullet? With his open-ended theme: stories by spec-fic authors w...