Fenric made my Top 10 TV Who Stories in that thread I made a few weeks back. Both Fenric and Ghost Light are very complex, multi-faceted stories. I find them a real antidote to a lot of the modern sci-fi out there that is practically screaming with pride about how dumb, cookie cutter and simplistic it is (Hi, Jar Jar Abrams!).
There is nothing "very complex" or "multi-faceted" about "The Curse of Fenric". It is, like "Star Trek", a straightforward, well-told story. And the only reason "Ghost Light" is "very complex" is because it's just not very good, and people mistake that for deliberate sophistication.