You can't tell a book by it's cover, but a good book cover can make a world of difference for writers and readers. Nevertheless, the elements that comprise a "good cover" can be rather nebulous. That's why this list is entirely my own. I am not being paid by anyone to make these selections and promote their book, nor is this representative of the Novel Rocket brain trust. I just happen to dig cover art. I know I missed some great covers; feel free to mention noteworthy ones in the comments.
At one time, it could be said that the Christian fiction market lagged in creative covers. But thankfully, things are changing. Historical / Amish / Prairie Romance-type covers dominate the market and, in my opinion, they tend to look... the same. This isn't to say there isn't good ones, but that after a while they look rather generic. On a bright note, however, indie publishers are making headway with competitive quality covers, notably, Living Ink Books and Marcher Lord Press. Anyway, this is my list and I’m stickin’ to it!
Honorable mentions: The Ale Boy's Feast, Winter, Vigilante, Kiss of Night, Hero in Hiding, The Baker's Wife, Corus the Champion, Roadside Assistance, The Inheritance of Beauty.