I'm about a third of the way through Chretien's first romance, "Erec and Enide". Speaking to the original question of who was the greatest knight, I'd say it changed from story to story. In this particular romance, Chretien ranks them within the story, putting Gawain first, Erec second, and Lancelot third. Of course, during the story, Erec goes back to his own kingdom and becomes king, and does not remain as one of Arthur's knights.
The story doesn't follow the normal "beginning, middle/climax, end" sequence of modern stories. What seems to be the main plot, at first, gets wrapped up pretty quickly. Then it goes on with pages and pages of describing the tournaments, celebrations, wedding, and so on that follows it... and I'm only on page 30 out of 86.
But I'm already seeing something very cool, that these stories are well known for. The knightly honor that is portrayed. When Erec defeats another knight, he takes him prisoner by commanding him to go on his own back to queen Guinevere to surrender himself, while Erec stays behind to finish business. Even when in the wrong, the other knight is trusted to do the honorable thing.
It also describes the tournament. Between the story and what I read elsewhere about medieval tournaments, it helps to frame the mindset of the knights of the time. The 12th century tournament wasn't a game or competition in the same sense we'd think today. It was practically a full-blown battle. Knights would divide up into teams on a field. The fighting could last all day, with specific areas set aside for resting safely. But they would joust in large groups, and continue fighting on foot with sword or mace... using their sharp weapons, and mail hauberks and shields (remember, no plate cuirass in 12th century). They tried not to kill each other, but it would still happen of course, and there are accounts of severe wounds, including head injuries that left people incapable of managing their lands anymore. Knights would permanently capture horses from each other, and if they captured the other knight, there would be an actual ransom, which may or may not include their sword and armor. Pretty serious!
![Shocked :o](http://modernchivalry.org/forum/Smileys/default/shocked.gif)
This comes up in the context of describing Sir Erec, as he is described in being so perfect in his knightly behavior that he doesn't bother to take horses or ransom from the knights he defeats, and instead focuses on continuing to fight to win.