What is Dr Who's best plot ever?

I have been watching Dr Who ever since I was a little boy. But the double episode I just finished watching was the best I have ever seen. EVER! It had pion, intrigue, suspence, drama, scary bits, tender bits, but best of all a story line that reflected time twists of plot to match a time lord. The episodes involve the Dr as John Smith in a love match with nurse Joan Redfern set in a public boy's school in 1913. The character of Martha is a wonderful development. I wonder if the next Dr Who will be a black woman too?