Older favorites for me are St. Elsewhere - first hospital show where they didn't save the patient every week, in fact if you were a patient in season one, you're in real trouble. I liked Hill Street Blues back in the day because the cops weren't always the good guys. Homicide: Life On The Street was a step above Hill Street Blues. Then, of course, there was The Wire, which tried to show the point of view of some bad people who had no other real opportunities in life. I liked Lost until it lost itself and got stupid. I think a smart way of doing TV now is to set a boundry and stay with it. We're doing five seasons - even if we're super huge, just five seasons and that's going to be the story arc. Lost would have been amazing as a 3-season show, but it went on for 6 and they were throwing WAY too many things into the show to fill that 6 seasons.
Twin Peaks would have been maybe the best show of all time if it ended with 1 season. We were never supposed to know who killed Laura Palmer. But the network forced Lynch into revealing it. He regretted it immediately and I think he intentionally made the show so weird that only diehards would stay with it. Can you imagine how much more legendary that show would have been if they never revealed the killer? I think it was supposed to end with Agent Cooper leaving town to investigate the death of another girl in another small town.