Here are a handful of books that would make my list, and that you should totally check out:

Plato's later dialogues- Parmenides, Sophist, Philebus

These are barely dialogues at all any more. You see Plato transitioning to a distinctly more didactic style. He completely repudiates and moves away from his "theory of forms" and gives complex accounts of cause, value, nothingness, and unity. If you don't want to be full of shit when discussing Ancient Greek thought, you must at least be familiar with these. They're also fucking goldmines for excellent metaphysics, should anyone be interested.

Process and Reality, by Alfred North Whitehead

In my opinion, this is the greatest work of speculative Philosophy and Metaphysics since Kant's Critique of Pure Reason. All of the things Heidegger and the so-called Post-Modernists call impossible for Philosophy to do to justify itself Whitehead manages to do. Ironically it was published the same year as Being and Time too.

Whitehead started as a Mathematician and Logician, co-writing Principia Mathematica with Bertrand Russell, but moved away from logic and logical analysis to speculative philosophy. He was there on the ground floor of the revolutions in quantum mechanics and relativity, and to date his book is the best general cosmological explanation of these developments. It has revolutionary theories of time, causality, development, subjectivity, physics, and God. It's a must read not to be full of shit in Theology, or any area of speculative metaphysics.


Religion and Nothingness- Keiji Nishitani

Fulfills the promise of nothingness based Ontology that Heidegger and the Buddhist tradition had attempted, and is simultaneously the most loyal and interesting successor to both in many ways. Revolutionary notions of Time, Process, Appearance, Reality, and Religion.

Anyway, that's all for now. Plenty I forgot. I'd be happy to go on about my issues with Heidegger or give more about Whitehead or Plato or Nishitani.