You choose a mantra by following your heart, intuition, or conscience.
Examine what results you want. If you want to travel to Egypt, FARAON and Egipto are powerful. Also, you will need to experiment with these mantras to see what works best for you, since everyone has different needs.
Mantras like FARAON work because they activate vibrations within the internal and physical bodies. Just as words convey conceptual meaning, likewise mantras facilitate intuitive and cosmological forces within our organism, so that we can arrive towards esoteric knowledge (direct experience).
Through becoming conscious of the psychological and spiritual energies present within the sleeping state, we capitalize on them for our own awakening.
You take advantage of the transition between wakefulness and sleep when you learn to meditate. Meditation properly performed requires controlled drowsiness, so that you enter the dreaming state with lucidity, consciousness, and continuity of awareness.
The following courses will provide you with the insights you seek:
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami