My go to reference for this is Search Party. The first season is the most engaging TV I've ever seen, the second season is still pretty damn good, but then the show got picked up by HBO and became total shit for 2 seasons. Like god I fucking hated season 4 of that show.
As far as movies go, I gotta go with Shrek the Third. 1,2 & 4 are all great, but what the fuck was 3?
I've never watched Dexter but I've heard ranged things about when to stop. Is it worth picking up for the first few seasons?
Yes I loved Search Party. Seasons 1,2,&5 are great, 3 isn't that good but 4 is literally the most annoyed I've ever been with a show ever
I think the og "canon" was season 1-4, but idk if it's really aged well. Absolutely banger opening theme tho
I always watch the opening and end credits. Probably the GOAT intro followed by True Blood.
Yeah the first five seasons are great, with season 3 being the weakest. Season 4 is regarded as one of the best seasons in television history. Personally I think 5 is underrated and often people stop at 4 because of the ending. I think if 5 was wedged in earlier, people would have liked it more. It was just overshadowed by 4 and Trinity being a fantastic villain.
Season 6 is where things really start to fall off. The show was still on 12 episode seasons and season 6 could have been condensed to less than 10. It goes on for a bit too long. Otherwise, it would have been a good season.
Seasons 7 and 8 are really bad. A lot of filler, the villains don't compare to earlier seasons, etc. It was the worst series finale until Game of Thrones. It's worth watching to set up New Blood, but you wouldn't lose much just by skimming Wikipedia for plot summaries and watching only a few of the important episodes.
Despite its ending, it's still one of the best brother and sister stories ever told on TV. It avoids copaganda, depicting cops as corrupt and incompetent. The depictions of forensics, however, are problematic and contributed to the CSI Effect.
I actually liked all of Search Party's seasons, but I can see why some people wouldn't. The roundabout chase scene made me completely lose my shit laughing. They probably should have killed Dori off and ended the show after 3 seasons, though.