Jesus said that the Father was greater than Him, He did not say that the Father was better than Him. The president of the United States is greater than I am, but he is not better.
When Jesus came to Earth He humbled Himself and became obedient, He became a little lower than the angels, He came as a man in the service of the LORD and therefore, called the Father His God (see Philippians 2:8; Hebrews 2:9; John 20:17). This refers to position and not to ontology.
This is an important post and you really should read the rest of it! Check out the graphic he included on the left that illustrates what you have when you reject the Trinity and Mariano does a great job explaining it in the article.
Trinity : Does the Bible Teach Theological Subordinationism?