I've always read the ProFootball Weekly Draft Guide. I have every one going back to about 1990.
It has always been good and as accurate as I think you can get considering it's published in March.
Since Joel Buchsbaum (sp?) died, I think they've lost a little umph, but still very good if you want a hard copy as opposed to Internet material.
I'd recommend that one. It's available at 'Books-A-Million' or 'Barnes & Noble' around where I live.
"When you watch him play, you’re like, ‘Oh God, he’s going to kill somebody,’ and that’s what I like about the young man.” ~ Jerome Henderson on Cowboys rookie safety J.J. Wilcox