If the goal is fitness and mental strength any dicipline with a good teacher will work. I'd go for whatever you have the most fun with and will keep up.
Everybody should have some basic self defense training, but the confidence spirit from training will allow you to walk away from just about any potentially violent situation.
Sure a grappler will have an advantage if a fight goes to the ground, but this is so rare for most people I wouldn't train for it.
As my instructor used to say...never ever, ever, ever, ever, ever, ever, EVER get into a fight. But if you do, don't loose
-spence