I've been reading through the Wayfair stuff from the past day or two & am reminded of why I initially got my son into taekwando. I recommend it for everyone. They'll learn self defense skills for sure, but the best thing they can learn is to yell when someone grabs them.
Many times kids do not say a word because they're too trusting of an adult that approaches them confidently. At our academy, each class has a section that teaches them how to yell and how to break grip. These two things might just save their lives and save you a lot of heartache.
kicks are nice punches are better but a gun in the buns doubles the fun.
seriously though any martial arts is a good work out, beats the gym any day for me.
But don't pick a fight announcing you are a 'black belt' in a weaker system. Other black belts won't hold back.
Also don't think MMA martials like Brazilian Juicejutsu, or Krav is the best. It really depends on where you train, your body type, skill and experience.
Best advice is to not pick fights and have several guns in your buns.
Guns