Oh god I'm thankful I don't have to choose between them lol.
In an ideal world we'd have both the EBA/Ouendan and a RH rep. Right now I'm at least hoping for a RH character because at least they're kinda likely. (If the leaked roster isn't all of it)
Ayumi Tachibana. I think it'd be cool to see how Sakurai would implement an adventure game/VN character. She also has the somewhat distinct honor of starring in a Satellaview exclusive title that wasn't just a remix of some other game like the Zelda or Fire Emblem Satellaview games.
Also acceptable is the main character of the other two Famicom Detective Club games (of which she is just a supporting character), but I don't even think he actually has a name.
Hell yeah! Easily my most wanted newcomer, even though he's not who I wanted in the polls. /v/'s been going around saying he might be in Project M. I donno if there's any truth to that, but I wanna see my main man in Smash somehow!
A random sidekick from Paper Mario would cetainly be obscure to the general public. Trying to stay realistic here. It's not like we are going to get some random NES character from a game no one has heard of.
Not that I believe a Paper Mario sidekick is gonna be playable anytime soon (PM himself has yet to fill that role) but I'd be surprised if "the general public" would be able to name half the characters in this roster. There's a reason why people upload videos challenging their parents to name every Smasher, and hilarity like Zelda (Link) and Sharp Shooter Shelly (Zero Suit Samus) ensues.