There are many good fighting arts out there. I have recently been intrigued by Systema. While being one of the combative arts, and therefore eminently practical, anyone who begins to dig into Systema will find that there is something deeply different about it compared to other combative arts. While combat and fighting power are critical and important parts of any martial art, every martial art tries to get there using often very different philosophies. We could take out a lot of things that might make Systema different from other martial arts, but the following quote from Vladimir Vasiliev gets at one of the most important points, I think:
I look at each training session as an opportunity to look deeper inside, rather than making the body into a tough training machine. The objective is to become more human, seeing our own weaknesses or letting your partner win at some points. In my opinion, the most valuable quality of a person is his positive disposition no matter what happens. Training sessions should be used to overcome pride and fear, and to gain humility and benevolence.
While physical prowess is undeniably important to the combative arts, things like pride and fear are the sorts of things that will destroy even the most physically fit.