Martial Arts: Which is the ultimate fighting technique?

In my experience, style is of secondary importance to the intensity of the training. Real situations unfold so quickly and, as you say, are unregulated. There are very few opportunities to truly simulate such a situation in a controlled environment like a MA school. Training for the situation is by far more important than the techniques employed. If you freeze, it doesn't matter what technique or style you have...you're beat. In my opinion, simple styles offer the best opportunity to effectively train the situations and become effective in a short period of time. Krav Maga is a prime example. Very little technique involved relative to traditional styles and is adaptable to a wide variety of situations. Most importantly, since is was developed by the Israeli military, it is geared towards intense, physical training is a limited number of techniques. Watch the Human Weapon episode about Krav Maga and you'll see what I mean.