My main vote went to Krystal from Star Fox, at first simply because I thought she was the one character out of the series that seemed to have the possibility to have a moveset unique to the series and not be a Fox "clone" style like Falco and Wolf were (and I'm not saying clone in a negative sense. Just that their moves have a similar vibe, moreso Falco than Wolf). Then, with the whole situation of her as a character being the target of a lot of hate and misuse, I really decided to back her up to try to let her get her chance to shine with Nintendo's best. I really think with some good thought she can be a stellar unique character for Smash if she's played up to her strengths as a staff user, a psychic, and a space-tech figther, all in one.
I've also shot a few votes in for Miles "Tails" Prowler from the Sonic series because he'd be like Sonic's Luigi and has been around just as long, being Sonic's one true running buddy, and also being part of the age-old Cruel Melee joke from years past. Tails also has his fair share of key character traits, namely his two tails for flight, his smarts and ability to use self-made inventions. He's been underutilized in his own series lately, sitting a lot of adventures out since Sonic '06 and Smash would be a great place for him to get back into the flow of things.
I shot one vote for Wolf from Star Fox fame but I kept it at that, since honestly I think he's got a big enough following as is and probably will be the next announced DLC character, so I'm focusing on the two above.