A friend of mine writes Christian fantasy books. His stories are a bit "older" than Medieval settings, but they do involve dragons and other Fantasy elements. You can check his books out if you like, his name is Bryan Davis, and his daughter, Amanda Davis just released her first book as well.
I also like the Wheel of Time series and most everything else by Robert Jordan. I used to like Anne MacCaffrey as well, but it has become harder for me to recommend since it strays pretty far outside Christian values. Recently, I found out about Naomi Novik who wrote a series of "what if" stories about the French revolutionary war with dragons. I haven't had the opportunity to screen her books yet, so I can't say if they are "clean". I don't know if that's completely in your range, but that's where my casual reading tends to hover.