Speed versus Power...
There are many debates that you enter into at your own risk...nature vs nurture...chicken vs egg...dog vs cat...In every aspect of life there is an example of this dualistic conflict, in combat sports it's the question of whether speed is more important than power. You should never start with a conclusion (really why they are called conclusions) however my opinion is that you NEED both to be a successful fighter and indeed every successful fighter I can think of has had both of these attributes at there disposal. However, if I had to choose just one it would be speed. Why? Well there are a variety of reasons which need to be explored in greater detail.
1. Speed can be applied to punching, movement or defence. Each aspect provides a multitude of benefits to a fighter.
2. Speed in punching may result in lighter punches being thrown. Lighter punches will require less energy expenditure.
3. Lighter punches can be thrown from a variety of less conventional angles and positions. This ultimately allows the fighter to create opportunity to attack which may serve to confuse their opponent disrupting their timing and rhythm.
4. Speed can be varied. Switching up and down through the gears can provide a broken rhythm for your opponent, making you harder to predict and counter.
5. Ultimately speed in punching will lead to a higher volume of punches being thrown. The higher volume of punches you throw, technically the more punches you should land and the more damage you'll inflict.
6. Speed in footwork will make you a very different proposition. You become more evasive, harder to hit, effectively a ghost of a fighter. Your opponent then wastes valuable energy just trying to find you in the first place.