The dominant planet in a chart?

So, my question is how can we find out which is the dominant planet in our chart? What are the factors it depends on? I've heard that it can be the most aspected planet or the ruler of the ascendant. Since my ascendant's ruler coincides with my sun's ruler (sun and ascendant in leo, which by the way are in conjunction) does this mean that the sun is my dominant planet? Yet, my mars and mercury (both in virgo) both make 7 major aspects which according to some astrology books can indicate dominance. Still, other books say that the planet which is closest to the MC is the dominant - yet, my closest planet is jupiter and it is in the 11 house which is not so close. So, I will be really thankful if someone can explain which of these is true and is it possible to have 2 dominant planets in your chart.