Only one of those is Japanese though, and it's not a popularity poll, but an expected characters list poll. Yes, there's a difference. Also, any spot below 5 is a no man's land of "runner ups," so the rankings after 5 mean nothing. The other two are Reddit polls, and Reddit is a primarily western, English based website.
No offense because you seem like a nice individual. But most likely based on what? Square is said to be the one that was the hardest one to work with, so who isn't to say that the other parties are as well? If Square would have so easy to get every other party together, then why did we not get more FF content in the base game?
Also, Akira Toriyama is said to be (and this is only something I've heard) being someone that demands his creation to be front and center with EVERY crossover. Something I'm firm to believe considering how they handle the Jump games, the crossover between Toriko Dragon Ball and One Piece and that Boom/Fortune Street comes off as more of a Dragon Quest meets Mario instead of the reverse... which would be a problem for a game like Smash.
I'm not saying that Dragon Quest is impossible but your most likely comes off as assumptions based on random text leaks right now
So again I ask. How is it most likely?
I don't understand the need for "no offense" unless you're getting mad about this, in which case there's no need to do so.
Anyways, Square Enix could bring in the required parties for Dragon Quest negotiation relatively easy. Right off the bat Square Enix and Amor Studio (run by series' director Yuji Horii) are on board because they want to promote Dragon Quest. Akira Toriyama isn't that much of a problem because he's apparently really chill with Dragon Quest (Remember that the Fortune Street games were developed by Square Enix, therefore their characters would be front and center), and Goku has been licensed out multiple times over the years, so I don't believe he'd be a problem. Sugimiya is the largest potential problem, but Nintendo has worked around him before and can do the same here, and if Square Enix really wants it, they'll find a way to bring him to the table.
Square Enix doesn't have that power in negotiations for Sora because it takes place primarily between Nintendo and Disney. Sure, Square Enix can join in on the side of Nintendo if they really want it, but it's still Square Enix and Nintendo vs. Disney, which is a 50/50 matchup at best.
And Sakurai is also good friend with Nomura yet we don't have that much FF content in.
The point is that Horii's friendships with Toriyama and Sugimiya can bring them to the negotiations table easier.
Dragon Quest negotiations are much more easier than Sora, and very likely just slightly harder than negotiations for Geno.