Aries or Leo?Who would win?

You are talking about Sun signs .. which are only 2% of the astrological personality.

All the Sun indicates is what kind of behaviors build self-esteem within the person, so your question cannot be answered from the Sun Sign.

But even if you had ALL of the natal chart for both individuals, all it indicates is how someone will likely be, psychologically, if they do nothing to change or grow over their life.

Leo. Leo’s will never let it go.