What is your favorite Doctor Who episode with David Tennant?

Never watched Doctor Who, and don't ever plan to. But David Tennant was great as Kilgrave in Jessica Jones.

"An Age Old Question" and "Bob's Your Uncle" were my 2 favourite Dr. Who episodes

Girl in the fire place

Season 2 Episode 2 "New Earth". That is my favourite episode of all time. Through the new and old series alike.

'Blink' is great , I remember covering my eyes cause I was scared as I was quite young then.
The one with doctor and Martha when they meet Shakespeare and it has witches, the Harry Potter references are delightful.

Human Nature/The Family of Blood. One of the more creative episodes in the history of the show.

The girl in the fireplace

probably midnight or anything where the Doctor acts like the Doctor should or anything with out Rose or that silly romance in it

Probably either Blink or Midnight.

I can't really narrow it down to just one but a few of my favourites are:

The Christmas Invasion
School Reunion
Rise Of The Cybermen
The Idiot's Lantern
The Impossible Planet
Army Of Ghosts
Smith and Jones
Human Nature
Blink
Utopia
Voyage Of The Damned
Partners In Crime
The Sontaran Strategem
Midnight
The Stolen Earth

I have two
The Girl in the Fireplace
Human Nature/Family of Blood

My least favorite was the one in which he faked an American accent (actually pretty well) and pretended to be a police detective. I liked the story arc much better in which Peter Davison worked with his brother as a veterinarian. So That is the type of doctor The Doctor is ;)
I think Tennant is a very good actor but since I watched the episodes when they were a week old, I don't remember Tennant's episodes well..