I was really into The Walking Dead, I read the comics, have a Rick Grimes bobble head and Daryl crossbow, several T shirts… But by season 6 many of the best characters were dead and the new characters were silly. I gave up watching it.
Dexter was great through season 4.
A show about a serial killer who murders serial killers and perverts was a pretty cool idea. Eventually the writing got wonky and I bailed.
Breaking Bad - started watching with my brother, then I moved away from home
Westworld - I like western, and it went in another direction
Archer - change in direction
Criminal Minds - changes in cast, and became predictable (like Scooby-Doo)
Grey's Anatomy - changes in cast, and became tooo dramatic (everyone has to die, or almost die, or get married etc.). stupid cliffhangers
South Park - I live in CE and don't get many of the US political stuff that's present in recent seasons
Dark, Legion - OK I didn't "love" these in the first place, but watched at least a whole season. too complicated to be engaging
Prison Break - idk
Arrested Development - got tired of waiting for the closing season, but I'll get to it
Black Sails, The Big Bang Theory, In Treatment, You, - I'm still planning to finish these
I never really got Criminal Minds the way they would start the show with a quote and the name of the show itself implied that it was going to be more intelligent or different in some way but it never was. In the final ep they have to blow up an entire plane because one of their team can't shoot straight to hit a target only a couple of metres away!
I watched True Blood all the way through it gets even dumber in the later seasons. I tried re-watching it last year but couldn't make it through Season 1.
Not a show I loved by any means, but I liked HC's portrayal of Geralt. I'm a big fan of the games and expected a lot out of the series, but could barely watch the first season. Gave up partway through S2 and still have 4-5 episodes left that I don't plan on watching.
The women in the games were rendered so beautifully and were stunning to look at, the best I've seen in any game. By contrast, I didn't find anyone attractive in the TV series, that seemed to be focused more on being diverse and purposefully casting very mediocre looking women for all parts.
The Ranch, I thought it would be like that 70s show with horses, but after the Danny Masterson stuff and the plotlines getting kinda boring I tuned out a few year ago.
I watched Hell on Wheels till about half way through the final season. The show started strong but then became a semi horror with an un-killable villain. Eventually they manage to hang him and for me that was it, finally done. There was still the main story arc which had been largely neglected that needed to play out but I was so bored by that point I just stopped watching it.
Homeland - I was surprised to learn that it was a vehicle for Claire Danes. I found her character annoying. I stopped watching when Damian Lewis' character was on the way out and the tone of the show changed.
Big Bang Theory - when they all started to couple up it killed the show and it became Friends.
So many...but here are a few that stand out to me:
1) Frasier - I stopped watching it regularly around Season 10. It just got "old" to me by that time. I did watch the series finale, though (To be honest, I didn't like it).
2) Law & Order (the original) - I just cannot watch the post-Jerry Orbach episodes...I have tried at various points and just cannot do it.
3) The Cosby Show - I really thought it was so funny the first couple of seasons, but then I felt it changed and I stopped watching it altogether when I went to college (Fall of 1987).