If you want an art that is effective for fighting when there is no other choice, then the lists are useless. Check what is available in your area. Go along and ask the instructors if what they teach can be used for self defence. Their answers should tell you whether you should join their class. If taught correctly, almost any martial art is good for fighting, and the deciding factor will be how hard you train. If the class is too far away, if you don't like the instructor, or what you see and hear seems fake, your motivation for training will be low.
Is it available in your area? No? It's useless to consider it then. Does the instructor answer a straight question with mystical nonsense? Don't waste your time with that kind of class. Have you found a method of combat you enjoy learning? Stick with it, because your motivation to keep training and improve is arguably the most important thing.
With all of that in mind, I'm going to tell you what should always be in a list of effective methods of self defence, ahead of any martial art, and what any responsible instructor will also recommend before coming to blows.
Run awayAm I suggesting that, regardless of how many years you have trained, you should always take the opportunity to escape a violent encounter? I am indeed, and the law is with me on this one. If you have the opportunity to run, and don't take it, everything that follows your decision is something that could have been avoided.
I'm not going to soften this one for you. The possible outcomes of a violent encounter include, but are not limited to, temporary or permanent injury or disfigurement, violent death, theft, abduction and lasting psychological trauma. You think you can win? Ha! No one EVER wins! You want to injure someone else, when it could have been avoided, and you call that winning? You think you can explain yourself in a court of law? You think you're ready to cope with revenge attacks?
No, forget all misguided notions of honour and check your pride. They could have a concealed weapon. Their friends could be around, somewhere. If you want to talk about honour and pride, talk first about what is the right thing to do. There are times when running away is impossible, and that is when you need the ability to fight. Otherwise, just don't be there.
Be niceWhat is self defence? If you're thinking of launching a counter attack or throwing an attacker to the ground, you've got the basic principle wrong. Those things serve a purpose, and that purpose, rather than a specific way of achieving the aim, is the essence of self defence. So what is the aim? Well, self defence is not about harming an attacker, but about avoiding harm ourselves. If we can avoid being harmed without causing harm, that is the preferred way. If a self defence instructor doesn't instil this wisdom in his students, then he is at best irresponsible, and at worst a charlatan.
Given that our aim is to avoid harm, it makes sense that we should be the kind of people that no one wants to harm. This doesn't involve being a doormat, but simply being a nice person. In reality, it's impossible to be someone who is liked by everyone, but that probably says more about the nature of others than it does about you. We can make an attack less likely, though.
To paraphrase Wong Shun Leung, the art of invisibility would be more useful for self defence than a martial art, because a martial art is a weapon. A weapon is designed to cause injury, not prevent it.
In aikido, Morihei Ueshiba enshrined the basic principle of self defence: subdue your attacker using the method likely to cause the least harm. Even closer was Sun Tzu's statement that the greatest victory is one earned without bloodshed.