This is an analysis of the A10-5800K and A8-5600K (http://www.anandtech.com/show/6347/amd-a10-5800k-a8-5600k-review-trinity-on-the-desktop-part-2/5).
AMD APUs will get the job done, but one thing to consider is power consumption. AMD chips take far more power than Intel chips. Over time, the money you may save by purchasing AMD will be spent incurring electricity costs.
I would personally take an Intel i3 or i5 process for an HTPC build.