Four Seasons of True Detective, a rewatcher's perspective
Season 1 - Louisiana
I think what made this season feel so potent and iconic was the driving force of the dual narratives; the lingering epilogue which tied together characterizations and loose ends until it was all characterization was as much a statement of intent as the occult references or the strange, crawling fears it all tried to provoke. You sort of hated our two detective leads by the time you were halfway through, but then, of course, you came to love them for even their hateful aspects. Everyone says it never reached this peak again and although I somewhat agree (though see Season 3 below), I think it was many factors that made this series sing. They didn't catch the frickin' guy when they were hunting him, they weren't as smart as they thought!
Season 2 - California
People were very hard on this one when it came out. Of course any follow-on was going to be a letdown. Lightning won't strike twice. But on a rewatch, I kept finding things I flatly loved. The bone deep hatreds of California, the completely crazed attitude of the greedy and powerful; anyone with power only wanted more, and nobody, nobody, had even a single principle or loyalty they wouldn't give up for power. The dream sequences were sometimes too on the nose (Vince Vaughn in the desert) but were more often an absolute hammerblow (Colin Farrell talking to his father.) Critically, the good guys didn't win this. There was no way they ever could. Ultimately I think the juggling act didn't hold. You'd see a decent scene, cut to another one, then back to the first, with the same characters going over the stuff they just did a minute ago. It sucked the propulsion out of it. With so many threads, it never felt like it really got moving, unlike Season One where even when nothing was going on, you could always pop over to the other timeline to see how it would come out.
Season 3 - Arkansas
This one is my case that, actually, the show still can reach the heights of Season One. This one uses a full on triple timeline, but you never get anything mixed up. Ali is wonderful, and through his lover's (and wife's, and ghost's) eyes you see a guy who you can still hate, but is worthy of love. This is what makes Season 3 special in my eyes. You can call it sentimentalism or shlock but the ghost explains it all in the last episode - the detectives were chasing a monster, but the thing that caused the crime, and the solution, and every ripple that stretched away from it, was love. Throughout the series, our hero insists to his son that his daughter Becca must be near. And we see a traumatic memory of him losing her at Wal-Mart momentarily, ready to kill everyone in the building to find her, weeping with them in his arms, so from then on he's saying "where's Becca?" and his son is fuming because he feels like he's going it alone, while the audience knows he's still in that Wal-Mart. And then at the end he is still in the jungle. Love does not provide him an escape. But fate does give Julie one. I was screaming at the screen for him to turn around and go back, not to go looking any closer. But of course, he was already gone. And him showing up on a beautiful day and having a drink of water is exactly what he actually needed all those years.
Season Four - Alaska
A terrific addition to the series; we felt the presence and saw the perspective of many critical women characters in Season Two, but they were California women, and True Detective, like any show that is about violence and abuse, is really about the hatred of women. Interestingly, we only saw glimpses of this in previous seasons. The disabled accomplice in Season One, exactly one episode depicting the abuse of the trafficked in Season Two, and...naturally ....the strange pink room buried in a vault in Season Three, which everyone finds years too late. In Season Four we finally see it face to face, and fully understand the pressures of poverty and environment (always the environment in Season Four) that, symbiotically, causes it to thrive and grow. It is the most monstrous of the crimes, and, at first it seems strange that it's so natural. But when you look back, the natural world has always been monstrous in True Detective.
Season Five
My pitch:
Two state investigators arrive at a prison work facility where a stabbing has killed one, injured another, and two prisoners are missing. The search for the fugitives reveals that this was well-planned with someone from the outside; and that they are not randomly causing havoc. Before they can crack the case, one of the fugitives kills the other before succumbing to their injuries. Two years later he emerges from his coma.