Since I am very drawn to great cover design, this is going to be super fun! I'm not sure how I'll narrow it to just ten, though :) (I'm going to try to include cover credits where I can.)
1. The Spirit Ring by Lois McMaster Bujold - you can't tell from the image here, but that ring is a shiny, silvery-gold. I used to troll the library bookshelves for shiny spines - I took this as an indication that it was a new book and therefore likely not to be something I'd seen on the shelves before. When I came across The Spirit Ring, and pulled that shiny new spine out to find the shinier - and kind of creepy- ring (illustrated I believe by Steven Hickman) on the front, I was sold! (It was a good pick, the book remains one of my favorites of all time!). Sadly this cover on the Baen hardcover edition with Carol Russo's design is no longer available and the ebook cover really doesn't inspire.
2. The Replacement by Brenna Yovanoff - this cover just screamed, "You have to have me!" when I saw it. Yovanoff includes the cover credits in her FAQ, photographer Jonathan Barkat and designer Natalie Sousa.
3. Bitter Seeds by Ian Tregillis - I completely adored the original cover of this book. I know it's been redesigned and it's fine but this original with art by John Jude Palencar was so fabulous!
(I don't have any of the below on hand to include credits, unfortunately.)
4. Miss Peregrine's Home for Peculiar Children by Ransom Riggs - the whole design of this book is fabulous but the cover is so eerie. Again it was one that I had to know more about as soon as I saw that cover.
5. The Town That Forgot How to Breathe by Kenneth J. Harvey - this book was so weird and the cover perfectly conveys that weirdness!
6. Ritual by Mo Hayder - this is the UK cover and it seems that all of the UK covers were revamped to suit this style at one point. I love it - I think it's utterly fantastic! I actually do own a copy with this treatment but can't get to it to find the credits.
7. The Glass Books of the Dream Eaters by Gordon Dahlquist - I've really loved each different version of this cover that I've come across. I can't find the particular edition I own and it wouldn't matter because the picture would never convey the full effect, but this cover is a great one as well.
8. Carrion Comfort by Dan Simmons - this one is a bit of a cheat because I've not finished reading it. I wanted to include it here because I so love everything about this cover and this style of horror covers from the late 80s and early 90s. The rereleased cover on this one is so dull by comparison.
9. Wither by Lauren DeStefano - I don't know what it is about this cover that makes it so haunting but it's definitely a favorite of mine.
10. 172 Hours on the Moon by Johan Harstad - holy moly, I don't know which version of this one is creepier, the hardcover or the paperback! This is the hardcover but the pb is equally as good.