As for the 2008-2010 specials:
1. "Planet of the Dead." I'm sure this is a shocking, unpopular choice. Truth be told, it's not a great story. It certainly doesn't seem special enough to be a special. But it's a solid story with an interesting premise, a couple of good guest starts, and a remarkably restrained performance from David Tennant. Plus, it has the funniest line in Doctor Who history when the authorities try to arrest the Doctor. "Right. I'm just going to go lock myself in this police box."
2. "The Next Doctor." The beginning is great, particularly when the Doctor thinks that he really is talking to an amnesiac future version of himself. But when the giant Cyberman robot starts stomping all over Victorian London like a rogue Zord from Power Rangers, they lost me.
3. "Waters of Mars." Really creepy monsters. A great, under-realized premise of the Doctor going kinda evil. But ultimately, this special is sunk by too much David Tennant overacting, particularly at the end. Which brings us to...
4. "The End of Time." Ye gods, this is bad! It's 2 hours of David Tennant & John Simm trying to out overact each other! Bringing the Time Lords back was cool but pointless. I did like the real meaning of the "He will knock 4 times" prophecy. But then the victory lap where he revisits all of his companions (1) strained my credulity to the breaking point and (2) felt a little gratuitous since we'd already had a big multi-companion get-together in "The Stolen Earth"/"Journey's End." (Plus, after the way things ended with Jack in Torchwood: Children of Earth, bringing Jack back for a funny little Doctor Who cameo just felt totally tone deaf. I've got tons of issues with Jack after that and it'll take a carefully crafted Torchwood return before I'll be able to stand the sight of his face again.)
Overall, I'd rank the specials below any of the modern seasons.
1. "Planet of the Dead." I'm sure this is a shocking, unpopular choice. Truth be told, it's not a great story. It certainly doesn't seem special enough to be a special. But it's a solid story with an interesting premise, a couple of good guest starts, and a remarkably restrained performance from David Tennant. Plus, it has the funniest line in Doctor Who history when the authorities try to arrest the Doctor. "Right. I'm just going to go lock myself in this police box."

2. "The Next Doctor." The beginning is great, particularly when the Doctor thinks that he really is talking to an amnesiac future version of himself. But when the giant Cyberman robot starts stomping all over Victorian London like a rogue Zord from Power Rangers, they lost me.
3. "Waters of Mars." Really creepy monsters. A great, under-realized premise of the Doctor going kinda evil. But ultimately, this special is sunk by too much David Tennant overacting, particularly at the end. Which brings us to...
4. "The End of Time." Ye gods, this is bad! It's 2 hours of David Tennant & John Simm trying to out overact each other! Bringing the Time Lords back was cool but pointless. I did like the real meaning of the "He will knock 4 times" prophecy. But then the victory lap where he revisits all of his companions (1) strained my credulity to the breaking point and (2) felt a little gratuitous since we'd already had a big multi-companion get-together in "The Stolen Earth"/"Journey's End." (Plus, after the way things ended with Jack in Torchwood: Children of Earth, bringing Jack back for a funny little Doctor Who cameo just felt totally tone deaf. I've got tons of issues with Jack after that and it'll take a carefully crafted Torchwood return before I'll be able to stand the sight of his face again.)
Overall, I'd rank the specials below any of the modern seasons.