+ ∞

As opposed to satellite or payed services such as netflix.

Already been mentioned, but Firefly, The Wire, Family Guy are all lauded shows that I too feel are excellent.

Alongside Family Guy I'd put American Dad, although it doesn't seem to have attracted the accolades that Family Guy has. Also, How I Met Your Mother and Big Bang Theory have amused me greatly over the years.

Slightly older, but I'd add Frasier to the list as well. An acclaimed show that I can watch and re-watch with ease.

I don't know, it's easy enough to list things that most everybody has or will watch but while I enjoy Family Guy for what it is I don't feel it's a good show. American Dad is a better show IMO but I don't get the feeling that it's very popular either. These two, however, are my friends. I also agree with The Simpsons. Early Simpsons.

I watched that for a while but found myself getting bored to hell of it and wishing they would just fucking explain it.

Community.

South Park

The Cape :(

Justified

Vikings

The Bridge

American Horror Story: Coven

Black Adder
Three's Company

The first season (and, to an extent, the second) drags a little while you get used to the characters and their interactions, but after that it's a crazy roadtrip all the way to Awesomeville with a continuous, cohesive story over 9 seasons (not 'The Wire' cohesive, but very good for a sitcom). Although it's quite a time investment, I'd say stick it out to the end of season 3 and then if you still don't like it, you can take some comfort in knowing you don't have to watch the other 6 seasons :)

Anything this guy is on. He makes me laugh.

QI
A Touch of Frost
Lewis
Hercule Poirot
Miss Marple
Midsomer Murders
Columbo
Firefly - Although i agree with it should be in the 'most overrated shows' thread too, i still personally think it is a very good show. It gets an extra +1 from me because it is one of the few sci-fi shows that actually caught my interest. I don't usually like the genre all that much.
Jack of All Trades - The campiness and cheesy humour might not be for everyone, but i love it.
Xena the Warrior Princess
Hercules the Legendary Journeys
Dracula (The new tv series)
Arrow
NCIS
Angel
The Pillars of the Earth
Avatar the Last Airbender
Merlin (the 1998 mini series that is)

My ex didn't like it though, she complained(!) that all the people in that show are so negative and complaining all the time. Irony.

Another ex disliked the British "The Office", saying that it is painful to watch as it is so close to reality. At the same time she adored shitty shows like Coupling (the original British version, not the US remake which was even worse) and Alias.

Maybe that is why they are exes, I love both Seinfeld and The Office (mostly the original British version, the US version is mostly (just) okay).

24 (Quality varied other different seasons but pretty sure it still had it's fans)
American Dad
Breaking Bad
Fawlty Towers
Futurama
Simpsons (though not near as much the last 5 years or more)