whichever one you will stick with and actually practice, there are not really 'more effective' or 'less effective' styles in general/as a universal measure, outside of specific contexts. boxers lose to MMA fighters in MMA matches, MMA fighters lose to boxers in boxing matches. its more important to know how to read a situation and de-escalate or escape than how to throw a punch or do a fancy flying spinny kick. make sure to study self defense laws in your area as well, you might be surprised at the standards you are held to in terms of responsibility to flee or de-escalate. for example in amerikkka it is a 'bad look' in a legal sense to draw a firearm and point it at an assailant without firing, with the intent to intimidate/de-escalate, because you are only supposed to draw your weapon when you feel your life is in danger, and the fact that you did not immediately mag-dump your assailant will be used as legally incontrovertible proof that you did not genuinely fear for your life, especially if your target survives after you shoot them after they refuse to back down from your hollywood intimidation check. also any sport martial art is going to habituate you into ignoring eye gouges and groin attacks and the openings for such, since they are universally against any boxing/mma rules and for good reason. ww2 combatives, such as Get Tough written by W. E. Fairbairn, inventor of the famous fairbairn-sykes fighting knife from WW2, will at least give you an idea of what kinds of moves are lethal, what kind of moves people trying to genuinely ambush/kill you might use, how people approach for an ambush, etc. however, as a legal civilian, you may want to learn something like judo or aikido to avoid legally (or morally) costly injuries to your assailants - good luck convincing the jury (or yourself) you were in the right when your malnourished desperate drug addict assailant who is half your mass ends up with his head caved in while you, the athletic larger guy with scary martial arts training, are unscathed. depending on your context you might want to look into self defense tools or weapons like stun guns, tasers, mace/pepper spray, or even firearms. as a side note, i recommend open-hand/palm strikes and chops over punches for people who have not seriously conditioned their hands for bare-knuckle boxing or muay thai or the like. even with perfect technique you may hit a harder area than you intend, and WILL break your hand/wrist on their skull/knee/elbow, and its better to 'only' break your pinky finger bones with a chop than the ones in your wrist/knuckles with a punch.