Depends on what you want out of it. Are you looking for exercise, self-defense skills, how to disable someone with practically no effort, looking to impress someone with some “ninja moves,” etc.?
When I was stationed in Japan 20 years ago, I found a martial arts course taught at our base’s gym. Ninpo Budo Tai Jitsu. I had never heard of it before, but they were offering a free month before you had to start paying for classes, so I figured I’d check it out.
Turns out, it’s not a self-defense course like I thought. It’s an assassination art. They said the goal was to kill your opponent as quickly as possible, before they had a chance to kill you. They made a point to say that we weren’t allowed to practice our training on each other or spar with each other, in case we accidentally killed someone.
Suffice to say, I dropped the course after my free month and signed up at a nearby Karate dojo. That was much more my style. It’s probably the most basic of martial arts. Gives you good exercise, some self-defense skills, and mental focus.
Definitely research different art forms and decide for yourself which works best for you. I’ve sampled a bunch over the years, but I think Aikido spoke to me personally now than any other form.