I kind of like my teams logo (1108) even though it is kind of terminator-like. I don't think their is a best overall, it's just what goes with your team. They're all unique.
Our it at our website:
http://www.usd368.k12.ks.us/ROBOT/index.htm
Look on the left.
Note: The picture is a gif so wait for it to load, but unless you have hi-speed don't bother to let the page load completely.