I would most definitely single out Rachel Talalay myself, if only because of Heaven Sent.
That episode is a visual masterpiece but I don’t think there’s a much better scene than the Doctor breaking through the wall, every single shot in that sequence is stunning.
This is always a hard question to answer, because I think a lot of great direction is because you can’t see the direction in a way. Good direction feels natural and doesn’t stick out, and usually if something really stands out it’s because of poor direction. Of course there are great Who directors like Camfield, Talalay, Harper, Maloney, etc. but I’m not sure I could exactly tell you what makes them so good. The writing, more than the direction, is what makes or breaks a story I think. Direction can maybe enhance something somewhat, or maybe a bad shot can take away a bit, but a poorly written story will be bad no matter how well directed it is, and a well written story can get away with a lot in terms of direction, and still end up fine.
One of the first stories where I realised I was noticing the direction was The Seeds of Death where Michael Ferguson does some really interesting stuff with his shot set ups and choices.
And I know it’s fashionable to mock Richard Martin a bit but there is a lot of clever directorial choices in his stories where he experiments with camera angles and the like for various effects. He might not always be successful but his ambition is admirable.
Aside from Talalay, I think my favorite director for the show overall is Jamie Magnus Stone, who I think did incredible work throughout 13’s era and I really hope to see him come back at some point.
But to highlight a particular sequence, I always find that the whole sequence in Fugitive of the Judoon from 13 and Ruth in the car up to the big reveal is absolutely incredible and just gorgeously cinematic, and I feel like Nida Manzoor never gets the credit she deserves for that episode
Unironically though, he did some great stuff. The scene in front of the London eye, the Auton massacre, “Run!”, the “narrows it down” scene, and this exchange: