I'm not a pro or anything and the best answers have already been posted out but another question that maybe you can ask yourself is why and what do you want to use it for??? It has been said that many factors will be in effect like money, distance, time, etc. Like is it for the art, for competition, for sport, for money, for health, to protect yourself and your family, to protect your country, etc., or just to be a thug???
Going a bit away from martial arts, I have met many weirdos, creeps and jailbirds that have not taken any martial art lesson but are very effective in real life fighting. Many of them learn their fighting techniques from their work, from war, the severeness of their living conditions, locations and surroundings, etc. and I have very high respect on their skills. I'm a bit shy to say but some techniques I treasure came from these guys. If you happen to accidentally see my blog somewhere, you'll have a bit of understanding on what I'm talking about. But please, this is not a good option so best to stay away from this kind of people or you might be polishing bars.
Next is obviously the BEST which is martial arts. Any art is good but it will be a big plus if you can find good teachers and good students that doesn't have their heads bloated with pride (thinking that they are the Last Samurai, lol) and where you can really enjoy their company while learning their art.
Next option are law enforcement and military fighting style/arts. I don't know much but their fighting skills have excellent reputation on bringing the bad guys down. But if you want to take another step higher is to join the special fighting forces. Techniques and style will vary depending on the country, their tools and where they specialize (rural, urban, open field, jungle, caves, tunnels, snow, dessert, rain forest, water, air, etc.). You will be a specialist in your skills but you will have to learn other stuffs intended not just for fighting and this is a huge area of study that you will have to do, endure and to live with it. This will cover about law, history, math, science, etc, survival, machineries, electronic, medicine, and the list just goes on and on. One sad thing that I read from some book that that there was guy who trained with these kinds of stuffs and it took him years to learn how to undo some of his training to live back again in the normal world. Surprise him by poking him on the back and his reflexes will go haywire and sends the guy on the concrete or get choked... It took his wife years before she can wake him up without keeping her distance in fear of getting accidentally attacked. But all changed when his baby boy was born and was a happy camper again
But I'm sure that there are many who got back normally I guess.
Again, there is no best single martial art or fighting style and all you can do is to start learning and be good with something but please do it with a good heart and a good purpose
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