I haven't read all the posts so I don't know if Kenpo was mentioned, but I've been practicing it for over 20 years and find it to be the most effective for me. About 10 years ago they started incorporating BJJ in with Kenpo at my school, because let's face it, most one on one fights go to the ground pretty quickly.
In a bar situation, Kenpo or Krav Maga is where I'll put my money. Kenpo is actually VERY effective for multiple attackers and is one of the very few martial arts that is geared for real street fights. Ed Parker, when developing American Kenpo, was very aware that he needed to restructure traditional Kenpo and modernize it for how Americans fight as opposed to Eastern cultures.
I've been in some pretty bad bar or bar type of situations and, in multiple attackers, I drew on several Kenpo techniques. Ultimately though, your goal should be to disable and leave as quickly as possible.
In all reality, you can train in any martial art you feel comfortable with and be very effective. The reason being is that, in an actual fight, you're not drawing so much on technique as you are on reaction and response. In other words, while not every martial art will teach you effective technique, every one will teach you critical thinking, proper balance and will quicken your reaction time. Those three things, in my opinion, are far more important than any technique you will ever learn.
Every Saturday I used to take my students and have them form a large circle. Then I would pick a student and have them stand in the middle and I would then point to 2-3 students and have them attack the student in the middle simultaneously. They could use any attack method they chose.
Most beginner students in the middle would try to use techniques learned so far in classes, and would very quickly be overwhelmed, but over time would learn that the technique became less and less important and that reaction and awareness became more and more important. That was the whole point. To have them put in actual situations where there really was little chance of escape, and that you would get hit and hurt, but to 1)quickly be aware of how many people you have to contend with, do as much damage to the immediate threats as quickly as possible, then work on secondary threats and finally to find yourself an escape route as quickly as possible.
Often times, when the student in the middle simply made eye contact with one or two of the students attacking him, the attackers would hesitate and have to rethink their next step. Much like a mugger would if he noticed you were suddenly aware of him.
So while we all have our favorite martial art, we should all agree that awareness, reaction time and balance are three of the things that just about every martial art will bring to the table when in a real life situation.
Growing up in Philly, I've been in more street fights than I care to even count and the more affluent and competent I became in martial arts, the more I learned that awareness, above all, was the key to stopping attack situations.
In closing, I know some of the readers here will say that most martial arts don't allow for "real world" fighting as they are in a structured classroom with minimal physical contact. That may be true for most martial arts, including Kenpo, but in the school I was taught, we always went all out. And when we sparred, we went full contact. I've broken two ribs, my right wrist and my nose three times in sparring and doing techniques.
BJJ is one of the most effective for one on one and Kenpo is most effective for a close quarters bar fight or multiple attacker.
Depends on the situation in the beginning with the aggression. If it is 1 vs 1 no friends involved to soccor punt you in the head. lol
If its a group, its better to keep your defensive up therefore you can see your surrounding and wait for them to be aggressive to move away from getting teamed on.. I'm no MMA fighter, but my friend told me once, while slap boxing to if you play defensively your just gonna end up getting hit less hard but getting hit more.. Depends on if you can handle it less, but its better to not get hit at all.