I know everyone's moved on by now, but I want to give this my two cents.
None of the DLC fighters were my “dream picks”. A lot of the characters I personally wanted were either already in Smash or simply aren't necessary additions. Prior to the DLC I had never played Persona 5, Dragon Quest, Banjo-Kazooie, KOF, Fire Emblem, Arms, Final Fantasy 7, Xenoblade Chronicles 2, Tekken, or Kingdom Hearts. So naturally the DLC picks didn’t do much for me on a personal and emotional level. But Smash doesn't exist to appease my tastes. When Sakurai picks a character that exists outside the bubble of the stuff I like, I keep an open mind and go about understanding why they would have a place in Smash. If their goal with the DLC was to expand Smash's scope by putting in video game icons from franchises with rich legacies, and representing a wide range of video game types, then they absolutely excelled.
Persona and SMT are both long-running, cult-classic JRPG series'. And Joker is the character, from this part of gaming, that has the most mainstream appeal.
Dragon Quest is a massively influential, monolithic franchise, That got it's start on the NES. It's inclusion was honestly a long time coming.
Banjo-Kazooie is like, the quintessential 3D platformer collect-a-thon, and is heavily associated with Nintendo.
Terry Bogard is the only SNK character on the roster, and is an icon of the NEO GEO console. Neo geo being a significant part of gaming's history. I will defend his inclusion to the death.
Minecraft. It's Minecraft.
Sephiroth is one of the most iconic villains in any video game, and his addition brought more FF7 music, which was much needed.
Tekken has historical significance, as it popularized 3D graphics in fighting games. Also, if you wanted Smash to have more villain characters, Kazuya Mishima is literally Satan.
And Kingdom Hearts is cool, I guess.
Other than that, there Byleth, Min Min, and Pyra/Mythra, all being from recent Nintendo published games. You could call them underwhelming, but they don't take away from the rest of the DLC. So overall, Sakurai and the Smash team delivered the goods. When people decry the DLC as a disappointment and say nebulous **** like "there's no real magic", I don't get where they're coming from. Like, what do they even expect from Sakurai?
Edit:
I decided I'd rank their inclusions from worst to best. (My personal bias plays a major role in this)