I cannot help but give my vote to 1717 the D'Penguineers and their 2011 swerve drive. I have seen
many swerve drives, in both digital media and in person, and the D'Penguineers have undoubtedly (this being subjective, of course) set the new standard in Coaxial Swerve drive-trains. Here is a
link to a video of them in competition, which is definitely worth a watch, ideally in HD. It's almost unbelievable how naturally and smoothly it drives.
Well, good luck on whatever you do build!