King Arthur and Merlin book recs?

I'm not really sure quite what I am looking for. I just finished the BBC Merlin series and loved it and have been itching to read some books with these characters.

A long time ago I had read some of the T.A. Barron young Merlin series and enjoyed it. I might pick it up again.

Not really looking for a retelling of the mythology.

But tell me what you liked and if you can, why you liked it :)