How it cannot be the one with the most character dev?
Marty goes from carrying a gun around Rust, to trusting him completely. We see how their relationship with Maggie ended, we see how each of them have to rely on each other in ways they didn't before, we see Marty become a serious investigator on par with old Rust. We see (ok, are told, vaguely shown) what happened to them during the years they were off the force and how they don't function without each other.
Basically the 95 characters hogged the previous chapters, with the present day being only barely touched during the interrogation, and we got to see the present day characters in full glory in this episode.