Talons of Weng Chiang Genesis of the Daleks Doctors Wife Girl in the Fireplace The Invasion(of the Cybermen) There's also a bunch of other eps that deserve mentioning. Dalek, Tomb of the Cybermen, Ice Warriors, Spearheads from Space, The Ark in Space, The Sun Makers, The Empty Child/Doctor Dances, Tooth and Claw, Silence of the Library/Forests of the Dead, and probably about a dozen others that I really loved.
Warriors' Gate and Ghost Light are special even if I don't know what happens a lot of the time. The Rings of Akhaten is similarly powerful if unsubtle in its endless singing, and does manage to further the story in between well enough, its not like the stories above are the kings of exposition, they rather spend the time for more detail, which this story does not have as much, while doing the equivalent of singing in the background.
Off the top of my head: An Unearthly Child - The episode, not the whole serial. Once the TARDIS lands in the past, the story goes downhill, imo. The Deadly Assassin Remembrance of the Daleks. Girl in the Fireplace Blink
In no particular order: Tomb of the Cybermen Genesis of the Daleks Inferno The Robots of Death The Silurians / The Sea Devils (which I regard as a continuum).
I watched Tomb of the Cybermen last night, this would probably be in my top 10, though it does suffer somewhat with datedness. This episode would make a GREAT big budget movie. Genesis of the Daleks is also a great episode, easily in the top 10! Honorable mentions: Horror of Fang Rock: This feels like it shouldn't be good..but it is! I liked Impossible Planet/The Satan Pit, Time of the Angels/Flesh and Stone, The Water of Mars, Silence in the Library, Vincent and the Doctor, 42.... I think from my recent sporadic rewatching of old episodes that I prefer the old Cybermen to the Daleks, and certainly to the new series versions. RAMA
1. The Tomb of the Cybermen 2. The Girl in the Fireplace 3. Remembrance of the Daleks 4. Terror of the Autons 5. The Doctor's Wife