If you were on the Equator, and the Earth's axis was pointed perpendicularly to the Sun, it would be: one of the Equinoxes, Summer Solstice, one of the solstices, or none of the above.

One of the Equinoxes.

Explanation:

In astronomy, equinox is the moment when the sun is located just over the equator of the earth.  Night and day have almost the same length on this day: 12 hours each.  This happens around 20 March and 23 September each year. Thus, the equinoxes are the times of the year in which the axis of the Earth, which is tilted, has no interference with respect to the way the Sun is located with respect to the planet: sunlight is distributed almost equally all over the planet during those days.