I thought I quit watching the first time after The Long Game, but now that I think hard about it was after Bad Wolf. Those two episodes both bothered me because in each the doctor just came off as a total cunt. In The Long Game he basically tells Adam to fuck off when he asks him to fix that brain-download thing at the end. And in Bad Wolf he seems to not give a fuck after Lynda dies (who I thought would have been such a better companion than Rose). This is why of the 8 seasons of the show I watched, I will always consider 1 to be the worst - I realize that opinion would probably change if I watched 11 or 12, but I'm not going to.
I didn't start watching again until series 5, which I thought (for a while) was almost - but not quite - as good as the worst of real Dr. Who. But then towards the end of the season it turned to shit again: The Lodger just plain sucked, and The Pandorica Opens/The Big Bang was full of the same sort of over-the-top not even remotely scientific crap that plagued the Tennant era. And Smith's doctor, who had been way more doctor-ish for a while, seemed to be getting more like Tennant's doctor in those stories.
I decided to catch up and watch the Tennant era during season 5, but I only watched them once and tended to put them on in the background while I did other stuff - so it didn't make much of an impression on me, other than to think it generally sucked.
I didn't watch again until series 8, and did the same thing with series 6 and 7 (watching them that same year 8 was going). I thought 6 and 7, while better than 1-4, were not as good as 5.
Finally, I started again with series 8. I had seen pictures of Capaldi as the Doctor and thought, at least he looks like the Doctor - maybe they'll finally get it right this time. I almost quit several times: Listen (started out good like they were going to introduce an interesting new enemy - but then the ending was such total shite), then there was crap like Kill the Moon... But there were also a few promising episodes like Mummy and Flatline, so I stuck with it.
But Death in Heaven was the end for me. With Missy and Cyberbrig, I decided Nupoo could just fuck right off. Cyberbrig bothered me more than Missy, because they had already fucked up the Master with Simm's version - which I actually think was worse. I never understood how people could like Simm's version of the character and then complain about Ainley's. Simm's Master makes even Robert's Master look like fucking Delgado's in comparison.
In the end, I've just decided the new series is NOT Dr. Who. Even some of the stories I like in series 5, they might be ok in and of themselves, but they are NOT Dr. Who. So stuff like: Eleventh Hour, Time of the Angels, Amy's Choice = good (or at least ok) NOT Dr. Who. Stuff like: Mindwarp, Paradise Towers, Happiness Patrol = bad Dr. Who. This would explain why I've seen Happiness Patrol over 20 times even though I think it sucks, and I've only watched Time of the Angels twice even though I thought it was good. Bad Dr. Who > Good NOT Dr. Who