How do Protestants respond to the JW interpretation of John 14:28? According to What Does the Bible Really Teach?, a Watchtower publication, pp.41–42:

The only-begotton Son never even considered trying to be equal to his Father. The Bible clearly teaches that the Father is greater than the Son. (John 14:28).

John 14:28 says:

“You heard me say, ‘I am going away and I am coming back to you.’ If you loved me, you would be glad that I am going to the Father, for the Father is greater than I.&quot;

Which, on the surface, appears to agree with the JW claim that Jesus himself says he is &quot;not equal&quot; to his Father.
What is the Protestant response to this, in the context of the divinity of Jesus.  How can Jesus be divine, and also &quot;lesser&quot; than the Father?
Good question, it is written


  "Let this mind be in you which was also in Christ Jesus,  who, being
  in the form of God, did not consider it robbery to be equal with
  God, but made Himself of no reputation, taking the form of a
  bondservant, and coming in the likeness of men." (Philippians 2:5-7)


Herein it says Jesus is equal with God (the Father), thus contradicting the watchtower quote you provided.   


  "And without controversy great is the mystery of godliness: God was
  manifested in the flesh" (1 Timothy 3:16 NKJV)


In John 14:28 Jesus is saying he is subordinate to the Father, but Philippians 2:5-7 says he is equal.  So Jesus is subordinate but equal.  To be subordinate does not mean one is not equal, for example the Bible admonishes wives to be subordinate to their husbands in the Lord (Ephesians 5:22), yet they are 100% equal in value in God's sight.  More info on Jesus divinity from Scripture found here - The Trinity.

Hope that helps!