S4 was great!
I love how every season ends with some major thing changing and the next season has a world where everyone is still in the same place and with the same relations (except when they're not), but the rules and context of the world have all changed and now we'll see how they deal with that.
Season 4 was an especially big leap, with a jump of several months ahead, and it made for a really fresh story, but with all the familiar faces.
Season 5 was less of a drastic leap, but is really interesting so far and very much not an abstract hypothetical fantasy story, but directly related to policing and how we run our societies.