1 Corinthians 14:1-4 ESV
Pursue love, and earnestly desire the spiritual gifts, especially that you may prophecy. For one who speaks in a tongue speaks not to men but to God; for no one understands him, but he utters mysteries in the Spirit. On the other hand, the one who prophesies speaks to people for their upbuilding and encouragement and consolation. The one who speaks in a tongue builds up himself, but the one who prophesies builds up the church.
The spiritual gift of prophecy seems more desirable than speaking in tongues with regard to building and strengthening the church body. Speaking in tongues is similar to prayer, a spirit to Spirit conversation between God and the believer. This is at the core of our relationship with God, whether spoken or silent, and gives consolation and assurance to the children of God.
Prophecy is the word spoken with a focus and concern for the people around us, that they may increase in the love, knowledge, and assurance that is theirs by the mercy of God. Speaking in tongues is a one on one communion between a person and God. Both reflect the grace of God.
The Son of Man left behind the perfect communion of the Trinity to speak the word into the ear of mankind. As the body of Christ on earth, we are to be and speak the word that is Jesus Christ. This is the tongue of the kingdom of heaven here on earth.
Speaking in tongues is a sign of our love for God. Speaking the word is a sign of our love for others.