cross training

I found this video on YT and I thought it was cool. Usually, DR/aikido demonstrations are done with DR/aikido people and very rarely with people trained in other arts. Because of this, one may wonder whether the partner's reaction is "realistic". Here we see two karate experts' reaction doing...

Why do you practice your current style? What about the style, gym, class, instructor or training culture keeps you coming back? For those who have studied multiple styles, why have you continued training in your primary style above the others? Why is it your primary style?

I'm currently training at a place that offers hapkido (which I'm currently doing) TKD, and arnis. There's also a school offering judo once a week($50 for 10 classes) not far from where I'm already training. My question is ultimately which would be better, crossing hapkido(mon-wed) and arnis(sat...