To get back track with the discussion, Geno's probably going to be an E3 reveal due to his fan favorite status at this point. Possibly with Crash for a double reveal if other rumors are true. Going by what we know from the physical fighter properties being shared with Bayonetta, there's a decent chance said character is female also just as ZSS was used as a base for Bayo. Some of the best candidates that could fit the description include Chun Li due to her iconic status as the first woman of fighting games, Morrigan from Darkstalkers since Sakurai wants to add as many potential worlds as possible, Taokaka and Makoto from Blazblue due to being significant fan favorites, and when looking at Bandai Namco, we musn't forget Soul Calibur as a possibility.
The thing is, after seeing DLC 4 being very lukewarm and 5 being the most controversial to date, you'd think they'd want to come out very, very strong for 6, even if it's not at E3, just maybe not E3 strong. I don't see a Soul Calibur, Blazblue, or Darkstalkers rep filling those shoes, mostly because I literally don't know the third, barely know the second, and do know the first, but I don't think enough people do (at least not in the West; I'll never claim to know what's popular in Asia or even Europe for that matter).
Chun Li is from a franchise we already have in Smash represented by a fighter and an echo. Requested or not, important to gaming history or not, I don't see her being a good first pick. I've already dissed on Crash being a bad first pick as well, but he'd be way better than Chun Li for sure.
TBH if Doomguy were to get in, despite having a deconfirm from the company (Banjo also had a deconfirm from someone who was directly working on something related to him getting in...), I think he'd fit the bill pretty well. Hayabusa (I refuse to call him Ryu in a game that already has a Ryu, sorry) might also, given his original legacy on the NES. Dante I'd say would also be a decent first pick.
What do I think would be the *best* first pick? Honestly, probably Geno, Waluigi, or Shovel Knight. I'm obviously biased on Geno but he's a long-requested 3rd party pick that exists in a 1st party universe. While he is highly-requested, he's also had an extremely weird history with Smash since Brawl's development. Waluigi on the other hand has been shunted to AT status, and this would break open the doors for AT promotion speculation while also giving many people their beloved Wah. SK not only does the same as Waluigi, breaking the hard deconfirm on ATs, but also breaks the door open for Indies, too.
TL;DR-ish: That's just my two cents. I feel that 6 will be an at least pretty well known, decently-to-highly requested character, and will kick off FP2 with a bit of a bang like Joker and Plant did with FP1 (even though Plant's not in FP1, it still kicked off DLC), and given how meh Terry's reveal was* and how awful Byleth's reveal ended up being*, I don't see yet another character people question and raise eyebrows at.
*PS: Talking about the reaction to the reveals on social media. Like em or not, you cannot deny Terry's was very weak and Byleth's was definitely explosive with negativity.
I hated how they handled Ridley's reveal in 4. Pointless secrecy is one of my annoyance buttons. Don't drag your feet on revealing something if there is literally no difference between the hint and the reveal. Like how they hid the face of the bad guy in Tropical Freeze, only to show him later and there was no surprising aspect to hide. They could have shown him at the start and everything would have played out the same. But Ridley's reveal was even worse. Don't dance around and make a mystery when a mystery doesn't have to exist in the first place .
I know it was meme'd earlier, but I'd like to bring it back up: Inb4 DLC 11 is a lukewarm SE rep that brings back Geno's Mii costume from Sm4sh.