I don't watch many TV shows and I will just quit watching a TV series if I am not enamored with it. Also, I make it a rule that I don't watch a TV show unless at least 3 different people recommend it to me. This seriously reduces how many shows I even start but it has rarely failed me. The following shows are the only ones that this has caused me to watch and my opinion of each:
Scrubs - one of my favorite shows ever. Great comedy and drama from start to finish. I am also a doctor and it is very medically accurate
Seinfeld - the greatest comedy series ever, IMO. I didn't start watching it until after they quit making new episodes. I am considering watching it again.
Breaking Bad - Simply the greatest series ever made. Plays out like an extended movie more than a TV show. I am currently watching it for a second time and it is awesome all over again.
Game of Thrones - This was ready to unseat Breaking Bad as the greatest show ever until they messed it up with the last season. Still awesome overall. Warning: The first two seasons are not as engrossing as later seasons but going through them is necessary and worth it. The third season is better but the fourth through the seventh is where it is truly great. Season 8 is the worst.
The Boys - Amazon Prime original and only one season completed but it is absolutely incredible. I cannot recommend it enough, especially if you are a superhero/comic fan.
Big Bang Theory - I loved it at first but quit a little over halfway through the series as the themes became repetitive. I had it recommended to me as I have a physics degree and love Magic the Gathering and Dungeons and Dragons.
Walking Dead - The first couple of episodes were awesome but then I lost interest before the end of the first season and have never returned. I probably won't either.
Sons of Anarchy - started to watch it but quit when my wife confirmed that every character I liked would die. Also, I considered Jace, the main character, to be an anti-hero and didn't like his character at all.
Stranger Things - I loved the first season but just haven't felt compelled yet to return and watch seasons 2 and 3 yet.
Dexter - my most recommended show ever (5 people) but I haven't started it yet
Deadwood - recommended by 3 people. Haven't started it yet. Of note, I live about 30 miles away from Deadwood and my first job was there.
Another issue is that my stay-at-home wife is a prolific show watcher and has either seen almost every show or cheats and watches them ahead of me if we start one together. She has already seen all of Dexter, Deadwood and Stranger Things and most of my TV time is with her so that is probably why I haven't watched them yet.