What is the best version of King Arthur and the Knights of the Round Table?

"Arthur Rex" by Thomas Berger was good. Kinda saucy, like the Middle Ages.

Best for what? Arthur, if he lived, lived during the start of the dark ages when the British were a Romanized Celtic people and the English were Angles and Saxons -- members of two germanic tribes which were invading and settling England. Arthur is said to have delayed the Saxon Conquest by about a century with twelve battles climaxing with the Battle of Badon Hill. Nevertheless he only delayed it. Many British fled to Nantes in France and the nearbye peninsula which became Brittany. Brittany fell under Norman Influence well before the battle of Hastings, where William the Conqueror conquered the Saxons. Many Bretons were in Norman Service at the time, and poet Robert Graves in his introduction to Le Morte d'Arthur has commented that indeed part of his popularity seems to stem from that, like the Normans he was a horseman who hated Angles.

Chretian des Troyes of course, and Mallory worked in the Norman Sphere of Influence.

Bluntly, the romances are fine writing but they are also political propaganda depicting Arthur as the type of the Just King until Tennyson's poems, the Idylls of the King, emphasized the sexual and other tensions of the stories and brought a more modern sensibility to them. Since that book there have been many many modern interpretations, often offering bold revisionisms: there is even one novel which goes beyond presenting Modred's side of the conflict with Arthur to featuring him as a gay rights figure.

Mallory is a good basis, in modern translation. I read Tennyson when I was about fourteen, and I strongly recommend it for teenagers. Yes he was a Victorian with all that implies, but also a great writer.

Mary Stewart's the Crystal Cave Sequence, which tells the story from Merlin's point of view, is a contemporary rethinking of it along traditional lines. I've always suspected Marilyn Hacker's Nimue to Merlin was based on it, and of course Andre Norton's Science Fiction romp Merlin's Mirror is definitely based on it.

Marion Zimmer Bradley's the Mists of Avalon novels are another rethinking incorporating a lot of feminist thought into the mix. Bradley was an interesting writer and though I prefer her earlier Darkover novels for a complex variety of reasons, this is one of the better versions out there.

The movies, frankly, I don't like. These include Excalibur which plays up the symbolic aspects of the story and King Arthur, which "tries to be real" and ends up looking like a badly recycled Alexander Nevsky (Eisenstein's great film).

The Mabinigion-the Welsh cultural source

The Clive Owen movie is so poor and so inaccurate, don't even waste your time.

I have been to Hadrian's Wall and it is nothing like the movie, never was

You do realize it is a cycle of myth and not novel correct?

I quite like the recent film version with Clive Owen. It is, in my humble opinion, the most likely to be close to the truth. But then, I am no expert, and I'm sure someone will be quick to correct me.

the porn version, it was made in the late 90's. awsome!