For no reason, here are some of my favorite episodes for each Doctor
1st: William Hartnell
Galaxy 4. The Aztecs. The Space Museum. The Web Planet.
2nd: Patrick Troughton
Power of the Daleks, Fury From The Deep (I would chop off my own pinky to make this episode magically reappear) The Web of Fear, The Enemy of the World, The Mind Robber, The War Games
3rd: John Pertwee
Spearhead From Space, The Time Warrior, The Claws of Axos, Terror of the Autons. Dr Who and the Silurians.
4th: Tom Baker
The Seeds of Doom, The Horror of Fang Rock, The Pyramids of Mars, The Robots of Death.
5th: Peter Davison
Castrovalva, Earthshock, The Caves of Androzani, Enlightenment, Kinda, Resurrection of…