Well, Erron Black and Sonya aren't as omnipresent online as the ninjas but they are both pretty damn top tier right now, I also hear great things about Geras.
As for the variations, they legit just need to allow edits in Ranked and Tournaments. I'd make the game even richer.
Watch any professional tournament and you will see all the Geras. You will find Erron Black online but its basically a coinflip if you find someone who plays him well vs someone who just spams his overhead/low moves. Either way he's infuriating to fight.