Q: I recite the Gayatri mantra. Recently I found an article which says for meditation the Gaytari is too long of a mantra and one should choose a simple one. If Gaytari is a powerful mantra why should not it be recited during meditation?
A: Let me explain briefly about the Gayatri mantra before answering this specific question. The Gayatri Mantra is part of the typical initiation of an upper caste boy. In this initiation rite he will receive the sacred thread and this will permit him to study the Vedas and to marry. At this ceremony the boy is then initiated into the Gayatri mantra, considered the most sacred of the mantras in the Vedas. He is then considered to be twice born. This mantra is then an obligatory rite for the life of the twice-born, performing it three times a day (first before sunrise, once near noon, and once after sunset).
The mantra itself comes from the Rig Veda, (III.62.10) and is three lines long:

(Om, bhur-bhuvah-svar)
Tat Savitur- varenyam
bhargo-devasya dhimahi
dhiyo yo nah prochodayat.
(om)
In English the translation of this mantra is somewhat varied, depending on the translator. Here is the basic translation from the Rig Veda (III.62.10) by the most reliable translator (Griffith): “May we attain that excellent glory of Savitar the God; So May he stimulate our prayers.” Others take more freedom with this translation and produce something like this: “With loving reverence we bow to the inner sun, the most marvelous light in all the worlds. Please illumine our minds.” Or here is another translation:
"We meditate upon the supreme effulgence of the Divine Solar Creator that he may direct our minds." Some traditions add a phrase at the beginning of this mantra: “Om Bhoor Bhuvah Svah.”
The Vedas and particularly the Sama Veda is filled with short mantras for recitation. But the Gayatri mantra is held to be the most powerful by many teachers. Some teach that Brahma produced the Gayatri before the creation of the world and that the Vedas were produced from this mantra. The 24 letters of the Gayatri are each given some significance, the general outcome of the recitation of this mantra being siddhi, or prosperity and success.
There are various opinions about mantras, as your question reveals. Several gurus and some of the meditation leaders in the West reserve the right to give a disciple his mantra personally. They hold that only your guru can lead you to true enlightenment and can give to you the mantra that is most appropriate for your enlightenment. This mantra will be a short phrase from the Vedas or the name of a Hindu god or goddess.
The issue of length can be important. A mantra should not be long. However, I think it would be too much to say that the Gayatri as a mantra is deficient because it is too long. The basic concept of a mantra is to wash the mind of negative karma and to rid the mind of distractions. The use of rosary beads (108 in number) and the repetition of a mantra hundreds, thousands, or even millions of times during japa is considered a type of sacrifice. It is considered useful in that it focuses the mind or even empties the mind to bring calm.
The basic sound of Hinduism is “om,” (aum) the primordial sound. The Supreme Being is held to be beyond comprehension, and the mind must therefore be transcended in order to reach Him. The three sounds in Sanskrit of “a,” “u,” and “m” are said to represent the waking state, the dream state and the deepest sleep state. The silence between each repetition of “om” is said to be the nothing of Nirguna Brahman.
To help you understand the issue you are facing, let me explain the concept of prayer from Jesus, which is really very different. Jesus actually said, “When you pray, do not use meaningless repetition, supposing that you will be heard for your many words.” (Matthew 6:7) The contrast Jesus draws to mantras is that prayer is to be meaningful and filled with content. In fact, the famous ‘Lord’s Prayer’ follows as He gives an example of how to pray. This prayer is given not as a mantra for repetition, but as a model for talking to God. This view of prayer assumes: 1) God is personal 2) our minds are our ally and should be active during speaking to God. The greatest contrast here is the place of the mind in prayer. Jesus is teaching that though God is beyond the complete comprehension of the human mind, the mind is not an enemy. Note that even those who advocate emptying the mind, teach men through their mind the reason they must empty the mind. In the eastern mystical view, the mind is almost an enemy to meditation and the goal is to empty the mind—to get around the mind in order to get to enlightenment. In the teaching of Jesus (who is eastern as well), the mind is an ally to speak to God and to communicate with knowledge and understanding to Him. Prayer is actually conversation with God, filled with your concerns and issues of the heart. With Jesus, prayer is relationship with God.
This should help to explain the reason that some advocate short mantras. If the mantra is too long, the mind has to struggle to recite the mantra. If the goal is to empty the mind and to get around the mind to enlightenment, then perhaps long mantras are problematic.