Michael Parenti
While many people are still (for some reason) recommending Communist Manifesto as introductory text, I instead point people to this every single time. Why? Well, Parenti is an extremely clear writer. Many Marxist texts are old, cumbersome, and expect the reader to have a high amount of historical knowledge going in--knowledge most modern readers do not have. Parenti takes things nice and easy, doesn't get too in the weeds, and keeps his books quite short. I guess what I'm trying to say is its very approachable. However, don't mistake its brevity for shallowness. This book is invaluable for beginners. Parenti does all the praxis for the reader, gives an acceptable amount of historical context, shows how left leaning movements are always systematically crushed by capitalism, the propaganda required to maintain the image of stability, introduces the importance of class, the ecological and human toll imperialism takes on the world, and wraps it all up very nicely with an invitation to aspire toward a better future and to continue educating yourself. You can read this one in an afternoon, and you'll be glad you did. Cannot recommend this one enough. RIP Parenti.
Rosa Luxemburg
This text is just getting more and more relevant each year. Reform or Revolution is a masterful and detailed critique of reformism. It is almost depressing how little extrapolation you have to do to relate this to modern day. I think this is a good book for more beginner readers to save them the heartache of getting swindled by a social democrat like Bernie Sanders did to so many Americans... TWICE! It is also quite short and witty. Rosa doesn't pull any punches, and is often outright rude to the Bernstein, insulting his intelligence frequently. This book is essentially a 'diss-track', but it is so well written you don't need to know who Eduard Bernstein is to get the picture. Rosa's passion comes through with a fury here which makes the book very gripping and entertaining. I found it impossible to put down once I started it. Another book you can easily finish in an afternoon, but will be thinking about for a lifetime.