I am sorry if I offended any Masked Man supporters. Just understand that not everyone sees eye-to-eye about the character being a worthy addition.
Personally, I would go with these:
- Two new series additions that are not in Brawl (whether it be Golden Sun, Advance Wars, Panel de Pon, Animal Crossing, Starfy, or Custom Robo, there are plenty of Nintendo franchises out there that need more recognition in Smash Bros. An Advance Wars character would easily be the most feasible if using Snake as a base, and overall is the least likely of all of those series to be granted a playable character in Smash 4).
- A DK newcomer (I am fine with Dixie or K. Rool)
- A Metroid newcomer (Ridley is probably the most iconic and important character from a veteran franchise not yet playable, yet Dark Samus would probably be among the easiest additions)