On the AMD side there is the Brazos E-350 based platform and on the other is the Intel Core i3-2100T.  One other choice would be to compare it to the aging Atom platform, which is missing some of the enhancements the more modern platforms have but is certainly energy efficient.  Check out who can score the lowest at X-Bit Labs.

"The variety of components for small energy-efficient systems keeps growing day by day. In this review we are going to talk about energy-efficiency processors: AMD E-350 (Zacate) and Intel Core i3-2100T (Sandy Bridge). We will also discuss new Mini-ITX mainboards: Gigabyte E350N-USB3 (AMD Brazos platform) and Zotac H67-ITX WiFi (for LGA1155 processors)."

Here are some more Processor articles from around the web: