First some definitions. Bhakti is devotion. Bhakta is the person who carries out the devotional practice.
The Gita looks closely at the practice of Bhakti, and identifies four basic types of devotee. Each of the four is grounded in a different basic principle, starting point and goal being sought. It is only the fourth one that represents the highest form of Bhakti in the Gita’s view.
Sri Aurobindo describes them: “There are those who turn to him as a refuge from sorrow and suffering in the world, arta. There are those who seek him as the giver of good in the world, artharthi. There are those who come to him in the desire for knowledge, jijnasu. And lastly there are those who adore him with knowledge, jnani.”
Sri Aurobindo next relates these four to the various motive forces of action in our being: “We may say that these forms are successively the Bhakti of the vital-emotional and affective nature, (The later bhakti of ecstatic love is at its roots psychic in nature; it is vital-emotional only in its inferior forms or in some of its more outward manifestations), that of the practical and dynamic nature, that of the reasoning intellectual nature, and that of the highest intuitive being which takes up all the rest of the nature into unity with the Divine.”
While each of these forms has its times, and its benefits in the spiritual development, the devotion with knowledge is considered by the Gita to be the best and highest: “For the Gita itself here says that it is only at the end of many existences that one can, after possession of the integral knowledge and after working that out in oneself through many lives, attain at the long last to the Transcendent. For the knowledge of the Divine as all things that are is difficult to attain and rare on earth is the great soul, mahatma, who is capable of fully so seeing him and of entering into him with his whole being, in every way of his nature, by the wide power of this all-embracing knowledge….”
Sri Aurobindo, Essays on the Gita, Second Series, Part I, Chapter 2, The Synthesis of Devotion and Knowledge, pp. 271-272