First place-

~ sticker
~ banner/ cover [optional]
~ shoutout
~ reads and votes
~ bragging rights
~ book added to library

Second place-

~ sticker
~ reads and votes
~ bragging rights
~ shoutout
~ banner [optional]

Third place

~ sticker
~ reads and votes
~ bragging rights
~ shoutout

For judges-

~ follow
~ shoutout
~ certificate
~ all candidates of the books they judge will follow back as well
~ any one of your book will get a shoutout