It seems that series that were renewed don't really qualify. And although quite a few have their good points the fans appreciate, whether they're gems is questionable. Have to agree about Wonderfalls and Miracles. Now and Again came close but serialization rendered its characters (especially Denis Haysbert's) bizarrely schizophrenic.
From way, way back, My Living Doll with Julie Newmar as Robert Cumming's robot.
More recent, Threshold might qualify. But I recently Netflixed a UK movie called Invasion: Earth that anticipated some of its better features. Still, the casting was genuinely gem-like!