In the classic French existential tradition Nietzsche looms very large, especially the explicit precedence of existence to essence, which is just a synthesis and concise restatement of what Nietzsche spent decades trying to say. It’s interesting that Kierkegaard has a stronger association with existentialism (I’m assuming you mean the French, ie Sartre, de Beauvoir, Camus) for you because for Kierkegaard, Husserl and Heidegger the subject has a primary role in the definition and expression of his essence, but he is not wholly precedent to it, he has an inherent nature. Happy new year to you as well.

In short, their philosophies are both centred on the primacy of the individual agent, who determines his life trajectory via his own imposition of his own will onto the world around him. They’re both the grandfathers of existentialism, though Nietzsche’s approach predominates among the French and Kierkegaard among Heidegger and his phenomenologist “spiritual predecessors” though more recently (ie in the last 40 years or so) the French existialist-absurdist and the German Husserlian-Heideggerian streams have, to a great extent, recombined.

I think Paradise Lost and Lord Byron’s Cain present nice counterpoints to one another. Also, Kierkegaard’s Either/Or (especially Diary of a Deceiver) and Nietzsche’s Thus Spake Zarathustra were the the first that came to mind, but these works aren’t so much two sides of a coin as they are two separate, winding paths to the same spot.

There are lots of great works of criticism that I could recommend, and they’ll help with a greater understanding of Shakespeare, but they’re not necessarily essential to begin reading. What I will say is that you should not begin with Much Ado, or any of his comedies; they are genuinely funny once you have a grasp of the Elizabethan/early Jacobean language, culture and social context in addition to a degree of comfort and familiarity with Shakespeare’s style; but comedy is much less universal than tragedy or history. What is funny is much more culturally and temporally particular than what is tragic, tragedy has a transcendent universality.

Also, of the comedies, Much Ado About Nothing is not my favourite, but that’s my own taste.

The Baroque Poem: A Comparative Survey is one that I quite like, it’s written well and has beautiful illustrations, baroque literature gets largely overshadowed by baroque music and the visual arts, and I think that this is a nice introduction. There’s also Runciman’s A History of the Crusades, I don’t necessarily agree with his thesis — that the crusaders were a sort of spiritual continuation of the barbarian invasions of Rome — but it’s such an important work for the historiography of the Crusades, which was still very much of the noble battle to assist Eastern Christians (sack of Constantinople notwithstanding) and protect the Holy Land against the depredations of the Saracens sort when he wrote, and he’s such a beautiful and engaging writer, he makes extremely dense material so very easy to read.

I bring a book, along with my notebook and pen, everywhere that I go. Of course it’s very rude to read at the table instead of speaking to your friends and family, but in any situation where it wouldn’t be faux-pas to use a mobile device, I think that it’s fine.

That said, manners are a context dependent social construct and truly it is the case that “impolite” is whatever your peers deem impolite or anti-social. So although it is logically incoherent, it might be the case in your family that reading is rude while scrolling social media isn’t.

Whales also have vestigial legs.

This isn’t exactly true, the King’s Press and the Scottish Bible Board are the only ones with Letters Patent to print the Authorised Version, which is the KJV with Apocrypha and without annotations or illustrations, any printer is allowed to print and sell the KJV without the Apocrypha or by attaching some annotations, a commentary or illustrations, they’re usually called Family Bibles or Illustrated Bibles and in my experience are the vast majority of copies of the KJV in England and Wales and Scotland.