One of the first things that Doctor Who fans ask when they meet each other is, "Who's your favorite Doctor?" It used to be the first, but it may have been eclipsed by "Old or new?" -- an unfair question, I think, as the two are more a pair of linked projects than one continuous effort, but you could argue either way.

It's very much a matter of opinion. Nobody's ever been a egregiously bad casting choice, although a couple of them were surprising, and some of the internal politics way back when kept some of the characters from really growing the way they intended. Six got pretty short shrift on television, where his tenure was interrupted by a series hiatus and then ended by a sea change in management far earlier than he was intended to go, but many of the Big Finish audios are brilliant. He acquires a companion who forces him to settle down a little, mainly because Evelyn simply will not be shouted down. Eight's only on-screen appearance was in a TV movie made in conjunction with a load of Americans and composed more of plot holes than anything else, but both Big Finish and the Beeb have picked up the character for an extensive and charming series of radio shows.

Me, I'm all for Five in the old series, and Ten in the new. They have a lot in common; there's a kind of buoyancy to both characters, as if the Doctor has just now realized he can be young again, and both actors are using an unusual amount of their own personality and body language, even by the standards of the role. Davison in particular is pretty widely agreed to have been playing himself, only with a time machine and a fancy coat. Despite all the conscious eccentricities, it comes across as very natural to me, something very easy to watch in the midst of all the wild special effects.

One thing that comes across quite clearly in both is the sense that the Doctor has come to enjoy being himself again. And that, too, is largely from the actors. Davison was not quite thirty when cast, at that point the youngest by at least a decade. He would have been eleven or twelve when the show started, right in the original intended demographic. (Fans have inquired; the Doctor he recalls being fondest of was the Second.) Davison was the first one to come into the role with memories not just of being an adult actor wanting the part of the Doctor, but of being a child and daydreaming about being the Doctor. There's a kind of magic to those memories; it fades with time, but most people cling on to just enough of it to bemoan their inability to get it back. There is little I find more absorbing than watching someone doing something he already loves, in the full knowledge that this is the closest he will ever come to literally, physically, living out one of those impossible things he used to fantasize about while staring out the window at school.

There's even more such continuity for David Tennant as the Tenth Doctor. Tennant was an unabashed Doctor Who fanboy way before he got anywhere near the show -- he apparently spent a lot of his early time on set dashing around playing with the console and working out what all the controls were supposed to do. He happens to have been just the right age that the Doctor he remembers most fondly was the Fifth. This led to some overexcited gibbering when Davison, who has retained quite an interest in the show and the fanbase since he left, turned up on set one day to see how the new Doctor was getting along. A lot of the body language Ten uses that isn't Tennant's own -- and, amusingly, some of the stuff that is -- has been borrowed from Five, most prominently his tendency to shove his hands into his trouser pockets even though there are perfectly good ones on the coat, and the way he looks as if he always wants to be going in all the directions at once.

It makes "Time Crash", the 2007 charity snippet, both hilarious and very sweet. It was written by Steven Moffat, another long-time fan of the show, from an idea he and Tennant came up with while being enormous geeks at one another during a party somewhere. It's clever on several different levels. It's a bit of a riff on some of the exceedingly hand-wave-y excuses that writers have used to get multiple Doctors into the act for various specials; it's a lot of Ten babbling a million miles a minute with no filter at all, and Five trying to reclaim his dignity by being grumpy; it's the Doctor getting away with breaking probably three or four major laws of time travel just because there's nobody around to see him do it; and, at the end, it's David Tennant getting to tell his favorite Doctor just how much of an impression he made, and Peter Davison getting to see just what kind of legacy he left.