I prefer the blue - grabs your eye and is easy on the eye. On the bookshelf, I'd imagine you want something to try and grab an eye and I think blue does the best job of this.
Quote from TimothySykes:
I have to know by August 1st, 2007 which one of the following covers you guys like most--any feedback is greatly appreciated!!
Quote from Longhorns:
You should use this as your book cover....
http://home.wamego.net/jaeklund/images/Douche.jpg
Quote from naifwonder:
I would go with the plain white cover. The blue gradient has somewhat of an old look look to it. The white looks new and sharp.