The second book on my Top 5 is George Eldon Ladd's A Theology of the New Testament, first published in 1974. Note the indefinite article; Dr. Ladd did not see his work, as do many scholars, as "the" theology, but rather a contribution to the field of New Testament inquiry. His explication of the kingdom of God in the gospels put substance to an otherwise benign sounding concept. And it was a breath of fresh air after having spent over 2 years in study at the Church of Christ sponsored Harding Graduate School of Religion.
After reading this book, along with those of several others then teaching at Fuller Theological Seminary, I quit my job at IBM and moved from Arkansas to California so I could study under such articulate evangelical scholars. The irony of all this is that on arriving at Fuller I discovered Dr. Ladd's teaching skills had deteriorated, and I was encouraged by fellow students to take professors other than Ladd. And I took their advice and never was in the classroom with him.
To understand "why" and the pressures of being an evangelical scholar during that time period, see Michael Bird's book review of Ladd's biography, A Place at the Table: George Eldon Ladd and the Rehabilitation of Evangelical Scholarship in America by John A. D'Elia.
Despite all the tragedy surround Ladd's life, this book is still a tribute to evangelical thought and one I still turn to ponder New Testament theology.