This fact constantly changes due to the range in the orbits of the planets located in our solar system. This depends on the day, month, and even year, which determines the position in orbit the planets are in. This can alternate between three different planets: Mars, Venus, or Mercury.
However, Venus seems to reign as the closest planet to the Earth for the most amount of time. Venus, which is the 2nd planet in our solar system, lies 162 million miles from the Earth at its farthest point in orbit.