The series have been fortunate to have some great directors. Two of them for me have done exceptional job:

Alfonso Cuaron and Mike Newell.

Cuaron introduced the world of Harry Potter to a more darker tone and it worked great. Also he done great job with the time travel.

Complaint for Cuaron: The first scene. Harry using lumos at Private Drive. He.Can't.Use.Magic.Outside.SChool!

Newell also introduced some great drama and the franchise best action sequences.

Complaint for Newell: Terrible treatment for Dumbledore.

Columbus was great for the first two movies, Yates was terrible with Order of the Phoenix, but got better with the rest.

My ranking of the films in terms of directing:

1. Prisoner of Azkaban
2. Goblet of Fire
3. Half-Blood Prince
4. Deathly Hallows Part 2
5. Deathly Hallows Part 1
6. Chamber of Secrets
7. Philosopher's Stone
8. Order of the Phoenix.

For me, it's Alfonso Cuaron!!! The sheer brilliance of the cinematography of the third film still has me in awe :3 Whenever I think of the HP films, its PoA that always stick out

I concur with Alfonso Cuarón being my favorite director in the series. His direction with Prisoner of Azkaban brought in a dark and gloomy vibe that fit with the theme. I would've loved to see his version of the future films. A close second is Chris Columbus, based on his previous films he always brings in the magic and family-friendly vibe to it which was perfect in introducing us to the world of Harry Potter.

Yates!!!