In case reviews of entirely different editions start to appear together (again), at Amazon software's whim: This is a review of the two-volume edition of Sir Thomas Malory's "Le Morte D'Arthur" published by Penguin Books, edited by Janet Cowan, with an Introduction by John Lawlor. Originally part of the Penguin English Library (1969), it was later (1986) included in the Penguin Classics, in both the older, smaller (mass-market) Penguin format and the current, somewhat larger format; they all appear to be identical in contents. It is now available in Kindle format, very reasonably priced. However, I will discuss other versions, notably the Modern Library, the Wordsworth Classics, and the old Everyman's Library editions.
The Penguin edition is based primarily on the 1485 text printed by William Caxton. It is modernized in spelling, but not in grammar. Each volume has a glossary of proper names, and another of archaic words; the most difficult words are generally noted and translated at the foot of the page on which they appear. A small section of notes in each volume deal with some confusing passages, and identify places where Caxton's text has been emended -- usually from the "Winchester Manuscript," now in the British Library, discovered in a safe at Winchester College in 1934, after being mistakenly catalogued under the title of a 1634 printed edition. The manuscript differs from Caxton's text in thousands of places, mostly minor, but some very important.
(Please Note: there is now another set of editions, based primarily on the longer Winchester text; unfortunately, modernizations of that version are either abridged, or, in my opinion, more or less open rewritings, or both, like Keith Baines' "rendition" -- not to mention John Steinbeck's unfinished "Acts of King Arthur ...," which is a retelling as a modern novel. Two complete old-spelling editions of this second, longer, version, are in paperback, the Oxford Standard Authors original-spelling edition, as "Malory: Complete Works," followed by a recent Norton Critical Edition, as "Le Morte D'Arthur," on somewhat different lines. I reviewed them together, under the "Complete Works" title, and more recently was able to post a review for the NCE, which used to be lumped in with other editions. Both are worthwhile, for readers willing and able to deal with them.)
Among the readily available editions of the Caxton "Morte," the Penguin edition is my favorite; a judicious balance of modern, or regularized, spellings, clarifying punctuation, and short explanations, without distortion of the not-yet-quite-Modern English of the sentences. Although Lawlor's introduction is beginning to show its age (Malory's French and English sources are treated as evidence in a then-current critical debate), Janet Cowan's text remains exceptionally attractive. The two-volume format is easy to handle, but can be a bit of a nuisance; if you want the whole story, be sure to order both! (It may be found to be more of a nuisance in digital form, where physical bulk isn't a problem, but navigation is.)
It was Caxton, the pioneer of English printing, who assigned the title "The Death of Arthur" to a work which begins with Arthur's conception and birth, for reasons which he rather laboriously explained in a final colophon. (For those of you who know enough French to see that the title should begin "La Mort" -- the spelling is, as elsewhere in the text, based on medieval *Norman* standards, and the Parisian certainty of Death's feminine gender did not dictate English scribal -- or printing-house -- practices in the fifteenth century.) Until the publication of the Winchester text in 1947, all editions of this famous late Middle English compilation of stories of King Arthur and his Knights had to be based, more or less (and often less) directly, on the 1485 printing by William Caxton, of which two copies have survived, one missing fifteen leaves.
Unhappily, most nineteenth-century printings (the first two both in 1816) were based on the very corrupt ("improved") 1634 Stansby printing, sometimes sporadically compared to the Caxton text, or were in some other way "corrected" for (mainly) Victorian readers. In 1817, the poet Robert Southey tried to rely on Caxton, but had to replace the missing pages in the copy he was using with those in one of the reprintings, in 1498 and 1528, by Caxton's apprentice and successor, the self-named Wynkyn "de Worde." (The first is the original "illustrated Malory," the second is the first intentionally "modernized" Malory, customers having apparently complained that a book written in the 1460s was sounding a bit old-fashioned.) In addition, Southey's publisher seems to have used Stansby as a printing-house copy, directly or through the competing reprintings of 1816. Uncertainty as to proper editorial principles, reflecting uncertainty as to Malory's literary worth, and concern over the "immoral" contents of a book thought likely to appeal to boys, continued through the nineteenth century. (And into our time, as well.)
The three-volume edition (with extensive apparatus) by H. Oskar Sommers of 1889-1891 finally used the surviving copies of the 1485 edition as the sole authority. I have not seen a reported reprinting of the full version The Sommers "Morte" text, without the introduction, notes, glossary, etc., is available in a hypertext format, and the Library of Congress site, archive.org, has reliable pdfs of all three volumes. It was presumably used by F.J. Simmons, who edited the ornate J.M. Dent edition of 1893-1894, illustrated by Aubrey Beardsley (reprinted a few years ago by Crown; Dover has issued an illustrations-only volume as well). Sommers' text was certainly used by Israel Gollancz for another Dent edition, the modernized four-volume Temple Classics version of 1897. This text appears to have been reset for a two-volume edition in 1906, in Dent's Everyman's Library series, with normalized (modern) spellings. There are some peculiarities in this version; for example, the spelling of names often changes between volumes one and two. For most purposes it was reliable enough, and was widely read during much of the twentieth century, appearing in the US in hardcover in Dutton reprints of the Everyman's Library, with a paperback edition in the 1970s. It seems to be out of print, but used copies show up regularly, and, some of the out-of-copyright Kindle and other digital editions may be based on it. Again, archive.org offers reliable pdf versions.
The Dent editions of the "Morte" had competition from other modernized texts, based on the Sommers edition, which included a revision by Sir Edward Strachey of his somewhat expurgated ("for boys") 1868 Globe edition for Macmillan. This version was replaced by a new Macmillan edition in 1903, edited by the distinguished bibliographer, and able editor of popular editions, A.W. Pollard. Pollard's text has been reprinted by a number of American publishers, and was at one time a Book Club offering, advertised as "unexpurgated" -- which it was, compared to some Victorian editions, and most especially to Sidney Lanier's "The Boy's King Arthur." The Pollard text is available on-line. It has been reprinted yet again, in the current Modern Library hardcover and paperback editions, with a fine new introduction, by Elizabeth J. Bryan, describing briefly the Arthurian Legend, and the problem of the two texts of the "Morte." The Pollard text also appears to underlie the Wordsworth Classics paperback, which has a helpful new Introduction, by Helen Cooper, and includes an index of characters (by Book and Chapter, not page number), but lacks notes. It is a relatively inexpensive, if not overwhelmingly attractive, alternative to the other editions. Once again, there are Kindle editions of Pollard's public-domain text, and pdfs at archive.org.
Although I prefer the Penguin edition if I want to read Caxton's text of Malory, the Everyman's Library and Pollard texts have deserved reputations as readable and reliable texts. Unfortunately, some of the digital editions are (as usual) badly in need of proofreading (ESPECIALLY in conjunction with the genuine archaic words and spellings), so some caution is advisable.
Since the appearance of the Penguin "Morte," there have been two major technical publications of the Caxton text: a facsimile, edited by Paul Needham (1976), and a critical edition, edited by James Spisak (1983). I am not aware of a popular edition which has taken advantage of these resources.