Meditation and prayer are the two fundamental pillars of the spiritual life, and it's safe to say that no spiritual practice can be effective if it doesn't include at least one of them. They do fulfil different functions, though, and here I'd like to consider what those might be.
Let's get some definitions in place first. What is meditation? Basically it is the attempt to still the endlessly active form-making mind to find out what lies beneath. (Or above, both are symbolically acceptable). There are various techniques designed to aid with this, ranging from concentration on an image, to visualisation, to repeating a mantra, to focusing on the breath and so on, but what they are all attempting to do is create an inner state of stillness and silence in which the rational ego-centred mind is bypassed and the bedrock of consciousness allowed to raise to the surface of attention. The outer world, which includes thought and the sense of self, is negated leaving only consciousness as it is in itself. In that state there arises a different kind of awareness, one seemingly not restricted to or dependent on body or brain. Whether that really is the case is another matter but the point is that the meditator enters into a state in which his normal everyday self is transcended or, at least, held in abeyance. So meditation, at its highest and not simply as a means to find some peace in a busy world, is for mystics. It is for those who wish to go beyond self to find a deeper reality in formless awareness.
But does it make you a better person? As always in spiritual practice everything depends on motive or intention so the answer to that is, not necessarily. It might bring peace, it might bring a measure of insight but, on its own, it is not going to make an egotist less egotistical. It might make us adopt an outer manner that is less egotistical and it might even make us act less egotistically and more lovingly or what, if I may say so, we assume is lovingly, but, as my teachers informed me, we still need to have the humbling experience of prayer. Meditation, at its best, will connect us to the God within, or the impersonal self considered as pure unmanifest being, but this is not necessarily going to change us fundamentally in the sense of the individual selves we will inevitably come back to. Yes, of course, it will affect us and we may appear and act and even think differently but, if we are talking about fundamental change at the root level of the ego, then meditation by itself is not enough.
There are two aspects to spirituality once we start to take it more seriously and move beyond a conventional outer religious approach. These are mysticism and sanctity. Meditation is concerned with the mystical side. It is a way of going beyond our earthbound self and accessing a deeper form of consciousness that can rightly be called spiritual in that it is not limited by the restrictions of form. But just as life is not just material so it is not just spiritual either. It's a combination of the two in the same way that we are and if we neglect this reality then our spiritual development will remain incomplete as does that of so many people practising the mystical approach. They seek God within as pure abstract being and neglect the transcendent Creator who is the personal God, union with whom transforms our individual selves. This is sanctification of the soul, and the way to it is through prayer. It is no coincidence that the Buddha is normally depicted with closed eyes, rapt in higher consciousness, but Christ has his eyes wide open, having united the two worlds of being and becoming, spirit and matter within himself. Christ did not teach the suppression of individuality but its transformation into a higher state that included all its good points, necessarily sacrificed in the pure being of Nirvana but in Christian terms remade into the new man. Now this transformation does require, in a certain sense, the death of self, as symbolised by the Crucifixion, but that is just the death of the false self, the self that clings to itself as a fixed centre separate from all else. Individuality remains as the fruit of the whole incarnationary experience and rises like a phoenix from the ashes, now transfigured into a higher state in which it is united with its source in God.
So meditation relates to mysticism and its practitioners tend to assume that the human being is consciousness above all and not much else really matters. But prayer relates to us as individual created souls who can become one with God when we have emptied ourselves of the stain of egotism. Individuality is preserved and we are made sons and companions of the Father, joined in love which is why he created us in the first place. Meditation basically rejects the created world but prayer embraces it because it is, as its Creator saw, good. I think meditation is important to detach us from our petty selves and give us an insight into the fundamental background of existence. But if we are to know God in his personal form, which was his intention in creating us, then we need prayer, and the essence of prayer is simple. It is always remembering the Creator, keeping him in our thoughts at all times. The constant remembrance of God or the divine presence is the deepest prayer.
Meditation is seeking the depths of your own soul as it was before you were born when it rested in God's being. But prayer is humbly acknowledging your Creator and inviting him into your heart. Both are good but prayer reaches beyond the impersonal to the personal, and the expression of the personal or individual is the whole point of creation and why there is something rather than nothing. God created the universe to express himself in love, and, while meditation might align you with the quiescent state of the world before creation, it is through prayer that you will come to know God as he is in his expressed state in which his glory is made manifest. Meditation is only half the story.