There should be no doubt there are many good introductions to Zen Buddhism in the English language. For ages the best was without a doubt The Three Pillars of Zen edited by Philip Kapleau. My personal favorite for many years and it certainly remains high on my list is Robert Aitken’s Taking the Path of Zen. Heck, I’ve even entered the field with a general introduction or two…
But I remain confident if you’re going to read one book the best probably is Martine Batchelor’s Principles of Zen.