Tilda,
It really isn't an "either-or" proposition. Each guide or reference material adds a dimension to your learning. Personally, I used the PM-Prepcast and the Exam Simulator in conjunction with a hard copy of the PMBOK guide and Head First. The Prepcast, PMBOK and Exam Simulator were the core of my study and Head First was a tool that put it all together in a way I could understand the material. It was also lighthearted and down to earth in its presentation.
Good luck,
Harry