I have a wide (and simple) taste in books: I read all kind of stuff, but mostly fantasy, sci-fi and mountaineering books.
My single favourite fantasy book is Tolkien’s The Silmarillion, a masterful epic in fantasy sauce. Robert Jordan’s Wheel of Time series is also quite amazing. Lately I have been enjoying Terry Pratchett’s Watch cycle and Brandon Sanderson’s Mistborn series quite a lot.
Major Bill Tilman was, I believe, one of the greatest explorers of the XX century, and his 15 books on mountaineering and sailing are among my favourite reads. His understated British humour, toughness and humility are legendary. Strenuousness is the immortal path, sloth is the way of death! During World War II, Tilman also acted as a connecting officier behind enemy lines in Belluno, coordinating weapons deliveries for the partisans. He described this adventure in When Men and Mountains Meet, one of his best books.
I also love Jerzy Kukuczka’s books, which provide a glimpse of an approach to mountaineering which was very different to that of the western alpinists. Kukuczka was the second man, after Reinhold Messner, to have climbed all 14 eight-thousanders.