This list is by no mean's definitive as my opinions regularly change when I re-examine various stories. Not all of these stories are what I would call flat out bad. What would your list look like?
1. The Gunfighters
2. The Dominators
3.The Time Monster
4. Creature From the Pit
5, Warriors of the Deep
6. Timelash (The thing is the premise of H. G. Wells meeting the Doctor is a really good idea and the villain probably could be really great. The Bandrils are kind of neat in a stupid sort of way)
7. Time and the Rani
8. TV Movie
9. Aliens of London/World War 3
10, The Idiot's Lantern (I get that a lot of people would say Love and Monsters but those people are wrong. Love and Monsters overall has better guest characters, a more interesting premise, a better message and thanks to ELO a better soundtrack)
11. Journey to The Centre of the TARDIS (This episode is very pretty but I find it kind of dull. I don't enjoy the guest cast, the monsters are pretty meh and it just doesn't leave much an impression. In a prior list I put Hide here but Hide has a really cool sequence showing the life of the Earth over milllenia that I think is great)
12. Sleep No More
13. The Battle of Ranskoor Av Kolos