What's the best prayer

The best prayer is the prayer of Gratitude. We are thanking for our existence, what we are enjoying now, like the fresh air, sunlight, unconditional love of nature, internal and external riches, experiences, relationships, everything that we have been given without any conditions. When we thank the Lord Almighty whole heartedly, it will decrease our ego and doer ship. The worst prayer is the prayer of asking something. There we are expressing lack of something. We are expressing insufficiency.
Thought is the first level of creation. Energy gets released there. Energy can never die. It stays and conglomerates with similar energies and creates your destiny. The nature or your sub-conscious takes things literally. When you say that you do not have something, your sub-conscious takes it literally and repeats "you do not have that". That becomes your reality. While gratitude makes our heart rich, prayer of insufficiency makes our heart poor, helpless and dependant. So, be careful. Your thoughts, words and actions create your destiny. Do not be fooled by yourself. Some people keep cribbing - "I don't have this, I don't have that", "If only I had this one thing... then the other.... then the other" –that only makes them poorer and poorer, inside first and outside later. If one is on a spiritual path, it is important to be happy with what we have been given and keep expressing sincere gratitude. This will make you grow spiritually higher and higher. Understand that the world can be compared to a mirror. It reflects what you are. A true master also does the same. You will be given what you deserve and not what you desire. What you desire may not be what you are eligible for. Let's be clear about this.
B. Prayer is for our self. We are praying to our self. That's why we mostly close our eyes while we pray, even if we visualize another form apart from our physical form. When we close our eyes, we are essentially going within. We are getting in touch with our self. Who is an external God or Guru? Extension of our self. There are no frames nor gender demarcations for God. God has no sex, color, or shape. He (and/or She) is in every being. He attains the color and shape of the bottle that carries him. So, when he sits in Ram's body, he attains the form and characteristics of Ram. When he sits in Rahim's body, he attains the form and characteristics of Rahim. When he is in a flower, he expresses that. Likewise a bird, animal, plant, tree, soil, elements, space, you and I - we all are the same God. So, where and why is the discrimination? Discrimination happens in our own mind, because of our sense of duality. Through normal senses that we posses, duality must exist. Through the extra sensory vision, unity exists. The vehicle to reach unity is meditation and the path is inside ourselves.
Through extroversion, we can only experience the sense objects. Through introversion, we can experience our Self. Once we experience our Self, all external sense objects become insignificant.
C. Through Prayer, we are reaffirming ourselves as to what we Are. Even though the object of our prayer is an external deity, we are essentially praying to our self and reassuring our own mind that there is a God, often not understanding that the element of the same God, our soul, is instrumental even for this prayer. God does not need your prayer. God does not have any expectations. So, if we do something believing that the God will be happy, it's utter ignorance. God is beyond duality, beyond gunas (Satwa, Rajas and Tamas). Everything began from Him and dissolves in Him. God does not care for your prayer or abuse. Only you get exalted by your prayers. God can only be attained through sadhana (spiritual practice) and elimination of our samskaaras (subtle impressions in the mind) through consistent exhaustion and avoidance of rebuilding them again. Here, the method is being in the present all the time. Through prayers or worship, we can only reaffirm to our own mind that God exists and He could be looking after us. God can be attained through internal exploration, meditation, elimination of vasanas (inherent traits and terrestrial bindings) and then, no prayers will be needed too. As we go beyond the need of external sense objects, or minimize their requirement, we get closer to the energy plane which is God.
Gross plane is an extension of God. Gross is part of God. We are also part of God. When ego dissolves and oneness takes root, we grow beyond gunas, we become all knowledge, we become the greatest bliss, there is no duality, we become all religions, or religion-less, we become one with all Gods, gurus. We reach the Creator. What happens then is that our only expression is overflowing compassion and love. Devotion to the soul element which overflows as bhakti (devotion), songs and selfless service. Our personal needs become minimal and the need of the universe along with its beings becomes predominant. We become one with God. One with the energy that Generates, Operates and Dissolves. GOD.