So I spent some time looking through all the entries, and I made my pick. It may not be the flashiest machine out there, but SwitchCade by TopJimmyCooks is truly innovative (The geared, slide-apart control panel is unique as far as I know.) What you need to consider is the versatility- A lot of those really flashy machines have more of a fixed control panel. SwitchCade isn't the only swappable panel machine out there, but it is among the very best at accurately representing the controls of the largest number of games. I have physically played on SwitchCade, and can attest to its solid feel and immersive, "real" experience. The auto-rotate monitor is pretty pimptastic, if not quite as unique.
Another thing is that SwitchCade was made by a first-time, low budget builder that got a lot of mileage out of DIY techniques and materials. This should be considered when the machine sits next to ones with beautiful, but farmed-out graphics.
OK, OK- so this is obviously a plug, or at least a plea. Suffice it to say that my last name is also "Cooks." However, I still employ everyone that votes to go by more than appearance, which does matter, but to also consider the deeper aspects and technical achievements, and unparalleled versatility that SwitchCade offers. Thanks!