Judo or Jujitsu can be very effective. The throws are great, but the real fight stoppers are the joint breaking techniques and chokes. Learning how to fall without hurting yourself is a bonus too. They call Judo the 'gentle way', but if you don't know how to fall there is nothing gentle about being slammed to the ground. The more vicious techniques were taken out of Judo for competition, like the neck breaks and throws that break joints at the same time. Competition typically isn't about maiming your opponent.
But the senior students and the sensei at the dojo I went to were also into firearms. They always said if someone pulls a gun on you forget jujitsu and shoot em first or duck and run.
