From what I recall of my reactions to the DLC characters:
: I didn't hate the choice, but I wasn't full-on "Plant Gang" either. I thought it was a fun, creative addition, though not one that I was particularly thrilled about.
: I owned Persona 5 on PS3, but I hadn't played it yet when he was announced. As a result, his inclusion was a huge surprise, though I'm not sure how excited I was about him as a character. (since then, I've played Persona 3-5, P4Arena, P5Strikers, and a 3DS game, so needless to say, his inclusion led to me playing the series and becoming a fan)
: my reaction to Hero was similar to my reaction to Simon and Richter - I recognized the historical importance of the series, though I hadn't really played much of it.
: dream come true moment for me. I'd wanted Banjo and Kazooie in Smash since I was 9 or 10, so needless to say, I was incredibly excited. Even going back to watch the trailer or people's reactions to it puts a smile on my face.
: OKAY! While my history with SNK was fairly recent (I had only gotten to play their games during the Wii or Wii U era; I got a Wii collection of the first five KOF games), Terry was my most realistic pick from the company (part of me wanted to see Rugal) and a really fun character, so I was glad to see him included.
: not great. The trailer likely didn't help matters (a good chunk of it felt like a slightly modified cutscene from FE Three Houses), and while I figured we might be getting a Three Houses character at some point (between the game's success and Sakurai being a fan of the franchise), I would have preferred any of the house leaders over Byleth. My reaction wasn't as negative as it was with Corrin, since I'd played and enjoyed Three Houses, but Byleth barely even felt like a character in Three Houses.
: all right. I'd played the free trial of ARMS and didn't enjoy it, but I know I would have preferred Min Min over Spring Man or Ribbon Girl, the faces of the franchise. (the guessing game that, from what I recall, lasted several months likely contributed to my lack of enthusiasm; there were only fifteen characters in ARMS, and only a few of them seemed like plausible options)
: his inclusion was neat, and I'm glad that they put him in Smash. I played the early versions of Minecraft (before Endermen were in the game), but I never really got into it like some people, so a lot of the excitement likely went over my head.
: amazing trailer and a complete surprise. The promise of more Final Fantasy content was a plus, and it likely helped that (unlike the time when Cloud was revealed) I had actually beaten Final Fantasy 7 and watched Advent Children by this point. My reaction was tempered somewhat by the implication that any other Square-Enix characters wouldn't be happening (there were a few that I was hoping for, whereas Sephiroth wasn't on my radar for Smash), but his reveal caught me off-guard and got me excited about what was to come.
: I liked how their inclusion was handled, and I preferred them as a choice over Rex (something about Rex's design and voice acting irks me a bit), but Xenoblade Chronicles 2 was a game that I couldn't really get into, and this is coming from someone who put over a hundred hours into Xenoblade Chronicles 1. I get why they were included (Xenoblade as a franchise seems to be a huge success), but from what I recall, my reaction was so-so.
: I really feel like they could have picked better music for the trailer. I'm not overly familiar with Tekken's music, but the initial song choice (while it's Kazuya's theme in one of the games) didn't exactly hype viewers up. While I preferred Heihachi, I could see the logic behind Kazuya's inclusion, and it was one of those cases where it felt long overdue, both for Tekken as a franchise and for a second Bandai-Namco character to be included. (my Tekken experience started with the Wii U with Tag Tournament 2 - I've played several other Tekken games since then, but I haven't gotten too deep into them)
: a fitting send-off to Smash Bros. Ultimate, and a character that I never thought would make it into Smash. I don't have the nostalgia for Kingdom Hearts that some people had, but I was happy to see him added and it gave me a reason to finish Kingdom Hearts 2. (I had finished KH1 and Chain of Memories, and started KH2, though this helped to motivate me)
It's unfortunate that my reactions to the first party picks were "so-so" at best and annoyed at worst. There are plenty of first party characters that I'd like to see in Smash (we're LONG overdue for a new Zelda character, for example), but none of the first party DLC choices wowed me.