In no particular order:
Angel -- a good season, imperfect but probably my favorite thing on. This was kind of like Season 6 of Buffy: the point of the story was how our heroes can be their own worst enemies. But IMO it was better-handled, leavened with more humor than Buffy managed and generally pretty good writing. It didn't hold together quite as well as an overall story as I might like, but that's a common failing of Joss: the season always comes together in the latter half. And the ending of the series was simply perfect: while I might wish to see more of these characters, I genuinely hope they don't do it, because it can only go downhill from here.
JAG -- disappointing. msmemory and I have been fans of this series from the beginning; we even endured the first dreadful season with the Blonde Bimbo sidekick. At its best, JAG combines a refreshingly sure moral sense with complex stories and solid writing. It's very much the way I'd like to see the US military: real people dealing with hard issues and trying to make them come out as well as possible.
But this season has instead been a painful reflection of the politicians' view of the modern military. It's been morally ham-handed, with far too many episodes reading like they were written as propaganda from the Defense Department. The military today is dealing with some of the hardest moral issues in a generation, and the show has given them only the most shallow and glossy treatments, usually find a cheap excuse to justify the politically convenient answer. There have been some good episodes, to be sure, but they have been cut by far too many that made me want to throw something through the television. I think the series has jumped the shark; perhaps fortunately, it's quite obvious that it will only survive one more season.
Joan of Arcadia -- the pleasant surprise of the season. I thought the high concept ("teenage girl talks to God on a regular basis") would be quickly exhausted at best, and more likely trite. Instead, I found that the writing is snappy and clever, the characters endearingly messed-up, and the theology surprisingly sophisticated. This is a series that deals with The Big Issues as they relate to day-to-day life, through the eyes of a typical but decent teenager who is happy to do good but often annoyed at how inconvenient that can be. It mixes stories of love, death, faith and family quite smoothly, with morals that are clear but rarely clumsy. The theological view is conspicuously ecumenical: while the leading family is nominally Christian, the story is rarely particular to that faith. The result is a bit new-agey, but sincere enough to pull it off. A definite keeper for next season.
NCIS -- quite possibly the reason that JAG was so bad this year. Don Belisario, the creator of JAG, wrote this spinoff series this year; based on the superior writing on NCIS, I have a suspicion that his attention was mainly focused here.
Like earlier JAG, NCIS isn't deep, but it's fun. The ensemble cast portrays a probably-idealized version of the Naval Criminal Investigative Service; the result is half military story, half cop show. The characters are quirky, to say the least, and they start off predictably one-dimensional (The Gothchick Labrat, The Gruff Lead Investigator, The Garrulous Pathologist, etc), but over the course of the season they've developed at least a modicum of depth. The dialog is sharp, and the plots are far more nuanced than JAG's -- this is a world where black and white aren't nearly so starkly drawn. There is moderate episode-to-episode continuity, but not enough to get in the way too much if an episode is missed. (With one or two serious exceptions: the season does have a principal arc underneath it, so a few episodes are key.)
Overall, a good series, better than I'd credited it from its pilot. I've been drawn into this one enough to stick with it.
Enterprise -- I know that some folks are very disappointed, but I rather liked this season. I never managed to find Voyager all that interesting, and eventually dropped it, but Enterprise has grown on me. This season was dedicated to a single ongoing story, and unfolded at a steady and solid pace. Like so much of better Star Trek, it was the story of our favorite starship fighting against Powerful Alien Forces. This time, they decided to make the show distinctly darker than it has ever been before, with Captain Archer confronted by some hard moral decisions; unusually for Trek, he doesn't always manage to find solutions that make everyone happy. It's a bit disconcerting at times, but refreshingly realistic seeing Trek deal with dilemmas that do not admit easy solutions.
If the series has one flaw, it is that the traditional Star Trek fondness for time travel stories is now bordering on obsession. There were, what?, something like five different time travel stories in this season alone, and the external timewar being waged several centuries upstream underpins the entire series. I am very fond of time travel stories, moreso than most people, but even I am feeling a bit sated. (And from the season closer, I don't think we're anywhere near done with the timewar story yet. I dearly hope they actually draw it to a conclusion next season, rather than continuing to shadowbox around it. Assuming, of course, the series gets renewed.)
Stargate -- always a favorite of mine, Stargate SG-1 is science fiction in the classic mold. This is a series with serious continuity, not so much episode-by-episode as ongoing story memory. As our heroes learn more about galactic politics (and increasingly mold it, with Earth finding itself dangerously central to an increasingly violent galactic war), the story develops ever-subtler shadings and possibilities.
This season was, to be fair, weaker than some. The writing is still good, but not as imaginative as it has sometimes been; it simply feels a bit tired. The entire season was wrapped around one large concept: finding the Lost City of the Ancients. (The Ancients being the long-lost race that built the Stargate network that ties the galaxy together.) The result was simply a tad too stretched -- half a season's worth of plot that took an entire season. Of course, they eventually find the Lost City at the end of this season, and that is clearly going to lead directly to this summer's spinoff series, Stargate: Atlantis. I'm cautiously optimistic: with luck, this will bring back the energy that has made SG-1 so much fun to watch.
MI-5 -- going back a bit, we get to this British story, which is due for a second season to show up in the US. This is seriously good stuff, darker and more honest than most US networks will dare to show. It is the story of a core unit at MI-5, the British domestic intelligence agency. Where American TV tends to whitewash this subject in the glare of jingoism, this gives a brutally honest (if still a bit glamorized) look at the life of a spy. The protagonists do their absolute best for their country, but they pay for it in broken lives. By the end of the season, our James Bond equivalent (the relatively young and dashing leader of the team) has lost love and honor; indeed, I'm not even clear how he's going to be able to continue for another season.
This is nasty stuff, not to be watched if you're looking for something uplifting. But it's some of the best damned writing on TV, and a refreshing antidote for the simplified American notion of intelligence. Gripping, scary, great story...
Dead Like Me -- finallly, getting all the way back to last summer, we come to perhaps the stangest story on television, the story of a teenage girl whose life doesn't really start until after she gets killed. After dying in a freak toilet-seat accident, Georgia finds herself working as a Reaper, one of the guides of the dead. But this isn't the usual mystical ooh-ooh version of death: the Reapers are Just Plain Folks, having to scrounge for a buck to make a living (Reaping doesn't exactly pay well), deal with cosmic bureaucracy, and in between try to understand at least a little of the cosmic system they work inside.
It's a surprisingly personal story, tightly focused on George as she begins to grow up in her new job. It's quirky, with gratuitously fancy cinematography and sometimes annoying hipper-than-thou writing. But it's consistently fun and witty, and doesn't require as much commitment as some series -- while there's a bit of ongoing continuity, the stories tend to be fairly self-contained. Well worthwhile, and will hopefully return...