Considering I didn't watch much TV until I retired, my list is longer than I expected.
Star Trek, TOS, TNG
The Ghost and Mrs. Muir, Here come The Brides
MASH
Sopranos
Some others, I'm sure, but the top two (tied):
Battlestar Galactica 2003, and Deadwood.
Deadwood scores a bit higher. Beyond the language, it's loaded with tiny grace note scenes that only become clear after multiple watching. I've bought one book about the making of it, and just donated to a kickstarter campaign for a new book. Both shows had gifted show-runners who had a real vision (most of the time...RDM got a little off track at times).
There's a longer list of shows that were favorites and didn't get the seasons they deserved: Firefly, Defiance, Forever, among others.
Galavant is one of those but it's in a class of it's own, a musical medieval fantasy tale that parodied, with respect, a ton of Broadway musicals.
I'm putting Sons of Anarchy and Justified on my list partially because they seemed to be in competition to see who could hire the most "Deadwood" alumni. Although "Fear the Walking Dead" is coming up close, since they've now had at least three "Deadwood" alumni on.