This is the sixth edition of Darwin's argument, the one he revised over a decade specifically to answer the scientific and religious objections that came at him after 1859. If you are going to read On the Origin of Species once, read the version its author finished defending rather than the one he first published.

Darwin builds the case from the ground up: the Galapagos work he did aboard HMS Beagle in the 1830s, then twenty more years of study, then natural selection stated plainly enough that a general reader can follow every step. It is a genuinely readable book, which surprises almost everyone who assumes otherwise.

Canterbury Classics binds it in the Word Cloud Classics format, a flexible cover that opens flat and takes a rucksack without cracking a spine, 608 pages in a size you can actually carry. Handsome enough to shelve, cheap enough to annotate.