There are lots to choose from, these days. Aldous Huxley's The Perennial Philosophy is a good overview of the thematic analogues in Eastern and Western wisdom traditions, as is Huston Smith's masterful book, The Illustrated World Religions. For Buddhism per se, I would highly recommend The Heart of the Buddha's Teaching by the eminent Vietnamese monk, Thich Nhat Hanh, who spent his long career in exile from Vietnam stripping a lot of the Far Eastern cultural accretions from Buddhism, so as to render it more accessible to the West. He has also done an excellent series of translations and commentary on the foundational Sutras of the Pali Canon, such as the Sutra on Breathing, the Heart Sutra, the Four Establishments of Mindfulness, and the Diamond Sutra.

My other favorite Buddhist teacher is Pema Chodron, an American teacher in the Tibetan lineage (birth name Deirdre Blomfield-Brown), who has published many books, including a detailed commentary upon the text of Shantideva's classic text "The Way of the Bodhisattva" entitled No Time to Lose.

The thing I love about Buddhism is its essential simplicity; you don't have to "believe" anything to practice. In fact, the entire, vast corpus of Buddhist teachings can be seen as commentaries on the Buddha's primary instruction: Breathe, Observe, Let Go.