The vast majority of my most wanted newcomers have either already been added to the roster, are currently assists and therefore extremely unlikely to make the roster this time around, or are simply so obscure that I never expected them to make the roster in the first place.
So I don't really feel entitled to be disappointed, per se, by any new inclusions. But there are a few popular and frequently discussed characters whose announcement would only cause me to shrug and think, well, that must be exciting for fans of that character, so that's good for them, but I'll probably never buy this challenger pack for myself. Granted, I might be convinced to buy them later on, as I did Joker, despite having never played Persona to this day and not being a fan. RelaxAlax sold me on the character and if the game is ever released on Switch, I may give it a try.
Keep in mind I don't bear any ill will toward fans of any of these characters, I just personally don't really like or care about them.
I'm ranking them in order from most to least... unappealing.
1. Sora
I'm not a fan of most JRPGs, but I'm especially disinterested in anything with a convoluted or nonsensical story. I also generally dislike certain anime aesthetic cliches like clothing with pointless zippers, buckles, chains, and belts. So despite being initially curious about Kingdom Hearts thanks to my childhood nostalgia for Disney, I've always been put off by the gameplay, story, and the aesthetic. I especially dislike Sora's character design. Everything from his voice and personality, to his silly costumes. He looks like a teenager's OC on Deviant Art circa 2002, who was then awkwardly shoehorned into a poorly written crossover fanfic after being redrawn with poofy red pants and giant yellow clown shoes in an attempt to make him look more Disney-ish.
On top of all that, taking into consideration that if Sora is added to the roster, then either he'll bring with him at least some not-original-to-gaming licensed characters and content (which I just really don't want in Smash), or half of what makes Kingdom Hearts what it is will be awkwardly ignored. My preference would be for the latter, and I'll go so far as to predict that if Sora were added, he'd receive a Smash-original revamped design, complete with a Smash logo keychain dangling from the keyblade in place of the Mickey emblem. Kingdom Hearts just seems like it would be even more difficult to license than FINAL FANTASY, and given how barebones and lackluster the FFVII content in Smash is compared the the fan service that most other guest fighters have received, Sora feels like a waste of a challenger pack.
2. Travis Touchdown
I have never played No More Heroes, and am not interested in doing so. Travis gives me an anime Deadpool kind of vibe, and I don't find him appealing or even interesting enough to say more than that.
3. Reimu
I only know this character exists thanks to her relentlessly vocal fans within the Smash speculation community. I just find the immortal and ancient(?) magical anime Lolita character archetype off putting, and I've never read or heard anything about her to convince me otherwise.
4. Dante from the Devil May Cry series
DMC is one of those series that I've watched trailers and reviews of, and never felt compelled to play it. I'm more open to Dante's inclusion now that the DMC games are finally being released on Nintendo hardware, and he is at least a fairly unique and compelling character aesthetically speaking. As long as he isn't as broken as Bayonetta was, I wouldn't really be upset about his inclusion, just kind of indifferent.
5. Ryu Hayabusa
Speaking of indifferent, I don't have any strong feelings toward Generic Ninja. Unlike every other series I've listed up to this point, I've actually played and finished Ninja Gaiden for NES. My impression was that it was basically Castlevania if it were less interesting in every way and too frustrating and cheap to be fun to play. That said, Hayabusa is a true gaming icon of the NES era and beyond, so I don't consider Koei Tecmo undeserving of the honor by any means. I'm sure Sakurai would make Ryu fun to play as, but he seems a bit bland at a glance.
6. Heihachi / other Tekken characters
I've played Tekken briefly, and it really only served to remind me why Super Smash Bros. is the only fighting games series I enjoy playing. Games like Tekken, Soul Calibur, King of Fighters, and Street Fighter just aren't very accessible to a novice such as myself, so I don't have any attachment to characters from those games. That being said, I enjoy playing as Ryu and Terry from time to time, and I understand why Sakurai likes to pay tribute to these classic fighting games. Plus, I know for a fact that despite having no idea who Heihachi is, my brother would really get a kick out of playing as a buff old man in Smash. I would probably buy Heihachi for that reason alone.
So there's my list. Honorable mentions go to pretty much any mobile game character, because I hate mobile games, but I don't have a specific character in mind.
Edit: Haha, I just noticed that it's been so long since I've posted here that I still have my old newcomer support buttons from the Smash 4 era.
Edit 2: Left out a word.