Other all the way. In a slightly particular order:
1. Slime from Dragon Quest! Slime is the mascot of the series (this long running, highly popular series), and Slime as a character is incredibly popular in Japan (and to a lesser extent the West. I for one knew of Slime and what it looked like long before I knew Dragon Quest was a thing). Plus: Slime's moveset would be pretty neat. I like Slime!
2. Bub from Bubble Bobble. The things I just said for Slime? They apply to Bub too! The Bubble Bobble/Puzzle Bobble/Bust-a-Move series is very long running and (though diminishing over the years) rather popular. Not Dragon Quest popular, but still popular. Bub's also another character who has quite a bit of prominence in the outside marketing universe (so people who either don't play video games or haven't heard of Bubble Bobble would recognize him). Plus: Bub's bubbles-and-rainbows moveset would be a delight!
3. So my first Final Fantasy game was Final Fantasy VIII, so that'll always be the game that has a special place in my heart. Because of this, I shoulb probably throw my other vote in for Squall, as Squall has the second-most likelihood of these three (I'm tempted to say the most likely, but Slime is really big and important you guys! Slime!). But I'm not throwing my vote in for Squall, because I'd like to get a bit better with representation for human characters in Smash and get another female fighter in. So my FF8 vote is for Riona Heartlilly. I mean, she was important in FF8 too, if not equally important to the game as Squall.