ROTJ had some of the best character development in OT. While Han’s character development in ESB was great, I think Luke’s and Vader’s character developments in ROTJ were even a level above that.
I disagree. The Luke/Vader arc was great, but it was the only significant arc in the film. The other characters were just going through the motions, shells of their former selfs. TESB had great arcs for all the main characters. Every character was in a very different place personally at the end of the second installment from where they started off. This puts TESB miles ahead of ROTJ in the character development department.