A lot of the fighting styles that aren't necessarily good for MMA are good in the street,
which makes sense because that's the environment under which they developed.
Aikido - Combined with a striking style, Aikido is good to avoid getting swarmed/rushed and putting you in position to counter strike.
Judo - Shoulder throw on the sidewalk could end the fight.
Karate - Focuses on footwork, and one punch knockouts to vital points that can end a fight instantly.
Also...
Wrestling - Control, neutralizes untrained grapplers.
Boxing - Speedy, overwhelming attacks that are hard to defend against.
BJJ isn't good for street fighting IMO. And I do have experience here.