"What Name Does the New Testament Emphasize - Jehovah or Jesus?"
This odd question cannot be answered by tallying up two names in two columns to see which one appears most frequently.
The NT is not a replacement of the OT. It is a continuation of the Hebrew Scriptures. The NT offers a culmination or presentation of multiple prophecies from the OT leading to, and surrounding the Messiah. One portion of the Bible is incomplete without the other.
Since the Trinity teaching is most popular among mainstream Western religions, the OT often ends up in the back seat by having the "unpopular" but important Tetragrammaton appear more often than any other name in the Bible. Here is a list of most popular names (i.e. 'male') in the Bible, according to this source: https://www.bonpounou.com/namesinbible.html):
"Most Mentioned Men in the Bible:
David - 1,118 times
Jesus - 973 times
Moses - 740 times
Aaron - 339 times
Saul - 338 times
Abraham - 306 times"
Should we then emphasize the name of "Saul" over that of "Abraham" in the Bible since it is mentioned more?
Although Jesus Christ is at the center of the NT revelation of God, it normally does so within the context of God fulfilling his will of the salvation of mankind through the person of Jesus Christ (John 3.16, Acts 4.12). Jesus never usurps the place of the Father, God (John 17.3, 20.17, 1 Cor 15.28). He comes in the name of God to do His will. All post-NT efforts to explain the trinitarian claim that Jesus was both God and man at the same time flies against the general biblical teaching of simple monotheism, which the Jewish people so adhered to.
Nowhere in the Bible is it stated that Jesus was "both God and man." Can anyone name a single scripture that makes this statement in clear language? In fact, the popular tripartite language has more in common with Greek philosophy than biblical teaching. We actually lose accuracy by superimposing a convoluted fourth century dogma over the simple original concept of the first century monotheistic doctrine.