Karate or Judo?? Please Help!?

[mmmmmmmm_mmm]

I can't choose whichone to get into.I've trained Taekwondo for like 2 years but it was pretty useless.
Now I have to choose between Shotokan and Judo.I want to train one martial art until I am like 50 years old.Right now I am 14.

PS.My goal is self defence.