I'll give it a go with my top ten shows ...
1.
Northern Exposure - Beautiful, unique setting (Alaska ; though it was actually filmed in Washington), with quirky characters. Walks the line of fantasy and reality often ... and so well. Not quite a comedy, not quite a drama, but a mix of both. And a great exploration of the human condition. It often felt that each episode ended with some sort of epiphany-like moment. Almost always on the right note, this show. Cicely is a state of mind ...
2.
Twin Peaks - Have only seen the first season, but it pulled me in; and the more I've watched it, the more amazing it becomes; flirting with being a soap opera, at times, and very complex, sometimes haunting, but often funny. Very cinematic and surreal. Like one of the characters remarks, "It's like I'm having the most beautiful dream and the most terrible nightmare all at once."
3.
24 - The real-time, hour-by-hour format is a great plot device, and it works because you end up caring about the characters. The editing, music, cinematography, acting ... all of it superb. A drama, a thriller, it keeps you tense and guessing. Very involving show. (And, I think, the best currently in production.)
4.
Are You Being Served? - Have been watching this for years ... it used to be on late-night (11 to 12) on the Indy PBS station, and I would watch it before going to bed, so part of it is nostalgia ... but it's just so funny. They do so much with so little (just two or three sets). Whether it be Young Mr. Grace stumbling through the door at just the right moment to solve whatever problem, or Mrs. Slocombe's hair color ... there are so many things that I love here, the characters, the setting, the humor. And I am unanimous in that. I wish there was a real store like Grace Brothers!
5.
Star Trek: Deep Space Nine - The best of the Treks, I thought. Rich and dark, and intricate, from the Bajoran and Cardassian (and the Maquis) political intrigue of the first two seasons to the Dominion War of the latter seasons, this show used continuity (unlike the other Treks, really), and a large ensemble of regular and supporting characters. And the station-setting made for a different (and, I felt, more home-like) feel. Probably the black sheep of the Trek family, but the one I enjoyed the most.
6.
Keeping Up Appearances - I love Hyacinth and her social-climbing. And I love how Liz and Emmet are constantly trying to avoid her ("Coffee at eleven? Thank you, Hyacinth!") And of course there's Rose, Onslow, Daisy, the "dishy Vicar!" as Rose calls him, and others ... and Richard, of course. All the more delightful because Hyacinth is an unstoppable force, and the fun comes out of watching everyone deal with her, and seeing what scheme or plan she's come up with next (to advance the notoriety of her and her candlelight suppers).
7.
Ballykissangel - Like Northern Exposure in many regards (except Father Clifford wanted to stay in BallyK, whereas Joel wanted to leave Cicely). But I feel it's different enough (most notably in the religious aspects of the show). Love the characters, the setting, the relationships ... and over all its (six, I believe) series, it was (and still is) one of my favorites.
8.
Now and Again - CBS cancelled this one after a single season. (Which, if they hadn't, maybe Dennis Haysbert wouldn't be President Palmer, so ... ) Eric Close was a 6 million dollar man (more than that, but ... ) and Margaret Colin was his wife, who he's forbidden to see. No one must now that Mr. Wiseman has been rebuilt. The chemistry between Close and Colin was tremendous, and Haysbert was excellent, and so was Heather Matarazzo. And the guy who played Uncle Roger ... a fun sci-fi show with the right amount of drama and romance, and very rewarding. I only wish CBS had given it a chance ...
9.
Yes, Prime Minister - A very intelligent show about politics, with PM Jim Hacker trying to do one thing, but Sir Humphrey trying to stop him. Machinations abound, and the dialogue makes great use of the English language. And the three leads are very talented and funny.
10.
Monarch of the Glen - I would've put The West Wing in this slot (had it not jumped the shark with Aaron Sorkin's departure). This show is in the vein of Northern Exposure and Ballykissangel (curiously, to me anyway, none of these three seems a copy of each other; they're all strong). And it's just an enjoyable. The cinematography of Scotland is beautiful, the music lovely, a quirky cast with smart plots and interactions based around the town of Glenbogle.