They don't rely on Kata dude: It's one part of the curriculum. Kyokushin has Kata too you know. There is no best. You need defense, offense, frequent training, resistance, and appeal to the fighting ranges. That's it. It doesn't matter if you take x, y, or z. You have to worry about the situations that you'll have to deal with. The arts you listed are all different. Firstly: Aikido is a throwing art. It's highly defensive but newer styles are adding new elements to make it more complete. It's based around using your opponents weight against them. It works well when combined with striking. Tae Kwon Do and Karate are both striking arts, that do have kata traditionally (Including full contact variants), but whether or not that is done more than sparring is dependent on the school at hand, and the home sub-style. Tae Kwon Do has a higher emphasis on kicking (Which can be advantageous for people with long limbs like myself) normally (Moo Duk Kwan and ITF are 50/50 with hands and feet), while karate can vary as well, but is almost 50/50 as a standard. Whether which one works is dependent on the person in question, their dedication, and skill. No styles objectively work for everyone, just as no styles objectively fail for everyone. Training methods are what make things fail or not. Sparring is important for self-defense, aka street fighting.