There is only one episode I distinctly remember from firefly. That episode was Jaynestown. This episode was clever, funny, and has some hard hitting moments while being a basic ship in a bottle episode. I think it is as model television as you can get with Firefly..... Game of Thrones and The Rains of Castamere? Just listing these names ... you know what I mean. What episode of Firefly ... what single episode of Firefly, is that type of all-time great?
The rest are hilarious moments like Mal kicking dude into engine or great characters like Saffron or Jubal Early. Though none of the episodes really reach that all time great like Jaynestown.