Boxing + Judo ftw.Since you seem to be concerned about self defense, I would say neither, instead learn boxing.
Excellent manoeuvring, striking, defence, grappling, throwing, fitness and resilience. Oh, and falling well.
Apart from the even more obvious (i.e., don't get into fights, and if you do, bring a gun)... it's probably as much to do with a student's ability to learn, and to put that learning into practice, as it is the art itself (or teacher, for that matter).