Well this really stinks

I figured it was coming sooner or later, but I will miss him in the role

Out of the ones they mentioned I would pick James Nesbitt, since I seen him in "Jekyll"

Source: http://www.scifi.com/scifiwire/index.php?category=1&id=61816

David Tennant announced that he will quit as the title character in the BBC's Doctor Who, after becoming one of the most popular Time Lords in the history of the BBC science fiction show, the BBC reported.

Tennant stepped into the Tardis in 2005 and will leave the role after four special episodes are broadcast next year.

Tennant made the announcement after winning the outstanding drama performance prize at the National Television Awards. "When Doctor Who returns in 2010 it won't be with me," he said. (Tennant speaks about his time on the venerable show in a video on the BBC Web site.)

Rumors have already begun as to who will play the next incarnation of the Doctor, including Paterson Joseph, David Morrisey, James Nesbitt and John Simm.

Tennant, the 10th actor to play the Doctor, left fans guessing about his return at the end of the latest season. In the last episode, which aired in the United Kingdom in July, the Doctor had to defeat his enemies, the Daleks, to save the universe. Almost 10 million people watched as the Time Lord apparently started the process of regeneration--but did not complete it.

Tennant will appear in a Christmas special, titled "The Next Doctor," before filming four more specials in January.

The Ninth Doctor, played by Christopher Eccleston, will always be my favorite. David Tennant isn't bad, but he's not crazy enough
It will be sad, however, to see him leave the show.

My favorite is still..........Tom Baker       

Then David Tennant

Then Christopher Eccleston

There are a  lot of rumors concerning his replacement.  I wonder who it will finally turn out to be?

Out of the choices I have heard, I will stick with James Nesbitt

Nesbitt sounds good to me as well.

Woo Hoo

The x mas special is coming soon, wonder how long it will take for us to get it

I will have it on x mas day though 

I'm hoping to be able to get it then, too.

It was a jolly jape of an episode. Typical Christmas special, eg a bit "lite" but meh, early-evening-fun-for-all-the-family viewing. I have to confess to not being as huge a fan of the Russell T. Davies episodes, much preferring the darker tone of the Steven Moffat scripts.

As for the new Doctor... Well, Tennant actually grew on me and has become my favourite incarnation. His character finally became far more 3-dimensional  with this incarnation, revealing glimpses of his true nature and aspects of his life (eg the future wife) which previous "monster of the week" scripts didn't touch upon. Also, the dark side of the Doctor, his inner fury and "destroyer of worlds" aspect - previously first revealed with Ecclestone and the sole surviving Dalek - were given free rein, especially the "punishments" meted out to the family in The Family Of Blood (series 3 episode 9): he traps the Father in chains forged at the heart of a dwarf star, the Mother in the event horizon of a collapsing galaxy, the Sister in every mirror in existence, and the Son suspended in time as one of the scarecrows to watch over the fields of England as its protector.

Genius.

New Doctor has a very tough act to follow, imho...

I agree Tennant will be a tough act to follow.  Hopefully they will make a wise decision in a replacement actor.

[Earthling]

I just got used to Tennant guy.... 

He's making 4 more stand alone episodes in 2009, plus the christmas 2009 special, and it will be that one where we see him die and reincarnate. The full-length series, with the new doctor, will then run in 2010.

In the last voting David Tennant beat out Tom Baker as the fans favorite Doctor

I still like Baker the best but David Tennabt is in a close 2nd

I am still hoping his replacement will be James Nesbitt....was impressed with him in the "Jeykll" series

I have the episode just have not watched it yet