"Girl in the Fireplace" has been at the top of my list since it aired, and while there are others that come very close (like "Midnight" and "The Eleventh Hour"), this one's still the winner.

I love the way the episode looks, I love Moffat's trademark clever dialogue, I love that Rose does not spend the episode giving Reinette the evil eye (Y HALO THAR, "School Reunion"), I love the costumes, I love the heartbreaking emotions involved, and most of all, I love watching Ten and Reinette together. Tennant and Myles have smokin' chemistry onscreen (no surprise there, given they started dating afterwards), and this episode exemplifies a key characteristic of the Doctor's I think a lot of fic writers miss: he's open to the idea of romance, but someone else is always going to have to make the first move. And boy, does Reinette ever make that first move.
( the rest of the days )
I love the way the episode looks, I love Moffat's trademark clever dialogue, I love that Rose does not spend the episode giving Reinette the evil eye (Y HALO THAR, "School Reunion"), I love the costumes, I love the heartbreaking emotions involved, and most of all, I love watching Ten and Reinette together. Tennant and Myles have smokin' chemistry onscreen (no surprise there, given they started dating afterwards), and this episode exemplifies a key characteristic of the Doctor's I think a lot of fic writers miss: he's open to the idea of romance, but someone else is always going to have to make the first move. And boy, does Reinette ever make that first move.
( the rest of the days )