If the Big Bang had produced equal amounts of matter and antimatter, it is likely that our universe would be very different from what we observe today. When matter and antimatter come into contact, they annihilate each other, releasing energy in the process. If the early universe had contained equal amounts of matter and antimatter, the annihilation process would have occurred extensively, resulting in the conversion of nearly all matter and antimatter into energy.
However, our observations indicate that the universe is primarily composed of matter, with little antimatter present. This asymmetry between matter and antimatter is known as the baryon asymmetry problem and is still an open question in physics.
If the Big Bang had predominantly produced antimatter, we would expect to see an antimatter-dominated universe today. In such a universe, normal matter would be scarce, and when matter and antimatter came into contact, they would annihilate each other, releasing energy. This would make it very difficult for complex structures like stars, galaxies, and planets to form, as the matter necessary for their formation would quickly be destroyed by encounters with antimatter.
In summary, if the Big Bang had produced an antimatter-dominated universe, the conditions for the formation of complex structures, including life as we know it, would be significantly hindered. Thus, the existence of our matter-dominated universe suggests that the initial conditions of the Big Bang favored the production of matter over antimatter.