Slave, Bondservant, Or Servant? (A Bible Translation Comparison)

Ephesians 6:5

(ESV)"Bondservants, obey your earthly masters with fear and trembling, with a sincere heart, as you would Christ," 

(LSB)"Slaves, be obedient to those who are your masters according to the flesh, with fear and trembling, in the integrity of your heart, as to Christ;" 

(KJV)"Servants, be obedient to them that are your masters according to the flesh, with fear and trembling, in singleness of your heart, as unto Christ;" 

Romans 1:1

(ESV)"Paul, a servant of Christ Jesus, called to be an apostle, set apart for the gospel of God," 

(LSB)"Paul, a slave of Christ Jesus, called as an apostle, having been set apart for the gospel of God," 

(KJV)"Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God," 

John 8:34

(ESV)"Jesus answered them, Truly, truly, I say to you, everyone who practices sin is a slave to sin." 

(LSB)"Jesus answered them, Truly, truly, I say to you, everyone who commits sin is the slave of sin." 

(KJV)"Jesus answered them, Verily, verily, I say unto you, Whosoever committeth sin is the servant of sin."  

At issue is how to translate the Greek word doulos.  Should it be translated as slave, bondservant, or servant?  The ESV sometimes uses slave, sometimes bondservant, and sometimes servant, depending on the context.  The LSB consistently translates it as slave.  The KJV regularly renders it as servant.  

ESV (English Standard Version)

LSB (Legacy Standard Bible)

KJV (King James Version)