El, Robin, Dustin, and Steve were great. There was a lot of heart there and they were the most fleshed out and...honest, to what they were without the writing sacrificing parts of them to drive contrived drama. I thought they handled Robin's reveal beautifully and in a relatable way, and thinking back on what that tally board actually meant to her and other aspects probably made her the best inclusion of the show's run.
Max and Will sit in the positive end as well, though not as high as they are sort of sidelined despite being the two best equipped to deal with the respective circumstances (Billy and the Mindflayer). The former is there for El to bounce off of and make Billy having sex jokes (and to cry over his death), while the latter is further kicked about in killing his passion and childhood he hasn't even gotten to have for two-three years, while only serving as a proximity alarm.
Erica and Lucas sit somewhat in the issue end not because they weren't great. Erica was awesome in her interactions with Team Scoops and her discovery of being potentially a bigger need than her brother was amazing. But the issue was that they were written into stereotypes where it was probably important to break those. Lucas is the black male best friend who self stylizes himself as a ladies man while giving terrible advice, all while being the comedic relief and little more. Erica is the typical sassy, rude, talk big, in your face black woman that ends up needing a (white) man to bring her down to Earth. There's plenty of great stuff in there and fun to be had, but it's something they could have dialed a bit back and made them less stereotypical and one-dimensional.
Billy made for a great villain, but the ending was a bit unearned. Yeah, he was abused and his mom left his abusive dad and it's sad seeing how he started as a very loving and protective child. But that doesn't change how much of a racist and murderous POS he was even before the Mindflayer came along. Or are we ignoring how he attempted to murder Lucas and others throughout Season 2 under his own volition?
Jonathan and Nancy were just boring. The sexism in the workplace hardly went anywhere besides the well done scene between her and her mom. Also a missed opportunity, unless I missed it, of having Mr. Conspiracy Cupid, them, and Joyce in the same room. I just can't see why they left them intact with the move happening and Jonathan staying with his family. At least these two were smart and thought of their siblings when things started going upside down.
Mike was just as unlikeable, if not more-so, than last season. Only redeeming factor was that by the end he had apologized and was trying to be better. He's also one of the three characters that was written as inept in communicating. Not one word about Hopper dragged on the TroubEl in Paradise subplot.
And the other two, Joyce and Hopper. Hopper was somehow back to alcoholism and always yelling and bullying everyone. El being attached to Mike and Joyce moving are understandable stress points, but these issues go way beyond those. Joyce on the other end doesn't communicate what she's getting at and uncharacteristically stands Hopper up for an out-of-the-blue science pow wow with the Science teacher. Plus running around everywhere before even trying to figure out about their kids, knowing these sort of things always revolve around them. Their romance, while having some foundation to it, felt unearned and felt just a vehicle to push the Byers out of Hawkins with a final knife twist to a well traumatized Joyce.
As for everyone else...sort of one dimensional and cartoony. Got your big, scary Russians (except Smirnoff RIP), your bigger terminator model Russian, the sleazy and corrupt mayor, your pig office workers, and the Deus Ex Suziena (kidding, Suzie was the best amount of cute and cringe and perfect for Dustin).
It's a tribute to the 80's, yes, but so many of the characters fell short or suffered due to that push.