This 72-page delight, written by a Burmese monk named Mahasi Sayadaw who is quite the big deal in the meditation world, is perhaps the easiest starting point for insight meditators, particularly those with an engineering bent.

It describes a longitudinal path to enlightenment through the systematic noting, and subsequent deconstruction, of reality. Although my practice has transitioned primarily to the more objectless Zen practice of Shikantaza, I still use the noting technique pioneered by Sayadaw when my monkey mind is particularly active. Even moreso than mantra (or Transcendental Meditation), the practice of noting cuts through unhelpful or repetitive thought patterns like a hot knife through butter. It's like a cheat code to a calm mental space.

Building on the noting technique pioneered by Mahasi Sayadaw, Sayadaw U Pandita put forth an updated look at insight practice in In This Very Life.

It's the same core teachings, but framed in a way that I found helpful as a complement to PIM (although I would suggest starting with PIM).

And then, the magnum opus of insight meditation, to which author Daniel Ingram refers as "an unusually hardcore dharma book." Do not start with this book. But, if you've gone a ways on the journey and are looking to take a very, very deep dive into all the phenomenological underpinnings of the practice, there is no more thorough look than here.

Ingram follows the Visuddhimagga, or the progressive stages of insight created by the Theravada Buddhists thousands of years ago and subscribed to by an increasing percentage of the Western medical establishment. There's something to be said for having thousands of years of user testing, II suppose. From the Arising & Passing Away of Phenomena (that first big "holy shit" moment of a meditator; for me my first out of body experience) to the Dark Night of the Soul (you know it when you're in it, and this book gives tips on how to get out of it) all the way to stream entry (the achievement of the first stage of enlightenment), MTCTOTB analyzes and articulates every stage on the path to enlightenment in detail. It's not for most meditators, but by now you'll know if it's for you.

Ramana Maharshi is the patron Saint of Advaita Vedanta. If the previous books were "meditation for engineers," Advaita Vedanta is more "meditation for artists." Or, another way of looking at it would be to say that the previous books are about facilitating a gradual realization, and AV aims for a sudden one, that you experience over and over. I think both are true in their way.
This accessible book is primarily a collection of talks he gave to his disciples throughout his life, which point in myriad ways at a core truth that one learns through meditation: that your Self is not who you think it is. Maharshi's meditation technique is incredibly simple: whatever you find yourself thinking about while meditating, or whatever troubles or issues you find yourself with in life, simply ask yourself "who is having these thoughts?" "Who is having these issues?" And then really look to see the answer. Search for the self that is witnessing the thoughts and issues.

Depending on your experience in meditation, that is either profound or profoundly odd. But I promise you, there is nothing quite like learning who you truly are (and are not), and Maharshi is a pretty damn direct path to that realization.

If you come to meditation from a Christian background, there are meditative resources for you too, Richard Rohr being chief among them. Rohr is a Franciscan Friar, and in his book The Naked Now describes meditative realization that one gets from insight meditation in Christian terms. I grew up in Grand Rapids, Michigan, the mecca of the Christian Reformed Church, so while I am no longer Christian having this view on meditation was a useful perspective. This book is a valuable onramp if that's where you're coming from, and one of the most accessible of Rohr's works.

Or, if you're so inclined, you can strip out all traces of religion, East and West, and dive into meditative realization with neuroscientist, and devout and very public athiest, Sam Harris. His magnum opus, Waking Up, first disassembles all the worlds major religions as unnecessary, and then approaches insight meditation from a purely secular, empirical point of view.
While I've become much more spiritual since (as I've learned how much I don't, and can't, know), Sam's work, and this book in particular, met me where I was (secular humanist, intellectually-superior athiest) and brought my meditation down many levels. Can't recommend highly enough.

Or, if you prefer podcasts or actual guided meditations, Sam has a mobile app of the same name which packages his book in a different form.

The third of the "sudden realization" approaches to meditation was coined by Douglas Harding, who wrote the amazing interpretation of Dzogchen Buddhism titled On Having No Head. In my years meditating I have not seen a better, more accessible or accurate description of the process of sudden realization than Harding's. The testable reality that in all the world, from an experiential, first-person perspective (the only perspective actually available to us), every animal has a head except you. There's a space where your head should be, in which the entire world exists.

Think of this as a cross between Maharshi and Western empiricism, with a flair for the dramatic. Also, Harding disciple Richard Lang did a series of guided meditations on Sam Harris's Waking Up app to help you properly experience first person reality, which profoundly impacted my practice.

Finally, because many of the words I've used above are in the pejorative category of "woo-woo," and recognizing that many practical, empirical Westerners [points at self] can benefit from some overt, double-blinded scientific validation, I'll finish with the best scientific analysis of the benefits of meditation that I've yet discovered, Altered Traits: Science Reveals How Meditation Changes Your Mind, Brain, and Body. This book doesn't so much dive into how to meditate, the phenomena to look for, or the realizations you'll gain along the path of insight meditation, but what it does -- scientifically prove the value of meditating in the first place -- it does well.