Breaking Bad may be my personal favorite. It’s one of the few shows where I enjoyed all the seasons about equally. I never felt a “slump” in any part of the show. The Wire was phenomenal, never seen anything like it, but the fifth season was noticeably weaker (the “corrupt journalist” story didn’t do much for me).
A good show shouldn’t feel like the writers made it up as they went along (even if they did), and while Lost remains one of my shows, its tendency to feel that way in certain story arcs makes me hesitate to add it to this list. It’s certainly the strangest and most fascinating show I’ve ever seen, however.
Others where the strength of the writing shows:
Seinfeld
Freaks and Geeks
Mozart in the Jungle
30 Rock
The Leftovers
Homeland (first 2 seasons)
Arrested Development (original 3 seasons)
Parks and Recreation
The Simpsons (first 8 seasons)
I have not seen The Sopranos, The West Wing, or Mad Men, but I have a feeling if I ever do, I will consider them among the best.