I've had a couple of boards from ECS, both for AMD processors. The first was a Skt 939 and the second my current board (see my specs). Depending on what you intend to do, most manufacturers should be able to satisfy your needs.
One important factor that I take into account with motherboards is driver
support for on-board features, such as audio and graphics, with more emphasis being placed on the audio component rather than the graphics since I add a dedicated graphics card but use the built-in audio capability. Personally, I would recommend a board that has Realtek HD Audio for that very reason. Others may disagree with me on this, and that is their perogative, but I've seen numerous threads about audio problems involving c-media, VIA, and other codecs where drivers
are, in many cases, unobtainable. At least Realtek do update their drivers on a fairly regular basis.