I think it depends on the comfort level of the person. Some people could jump into it with Scott Cunningham's book first, because it looks "harmless" and safe.
Raymond Buckland's "beginner" book, is a bit more blatant.
Silver's beginner book trilogy was in-between those two.
Now if someone wanted to jump into and not look back they could start with Christopher Penzack's books (

they are some of the few that I've read where the author actually explains how to do certain techniques that are talked about in other books, but he's one of the few to actually walk you through it.)
Now...personally...I think any one book that is written by an author sympathetic to paganism that offers a basic covering of the beliefs and traditions...is the better place to start.
Me, I started with Scott Cunningham's book Wicca for the Solitary and Silver RavenWolf's Book of Shadows for the New Generation (you know, the big brown thick book), and Cunningham's Encyclopedia of Magickal Herbs.