This is one area I think S3 wins. Big Arm was a fucking colossal final boss, it looked the most predatory and deadly machine you had to face. From facing down the cannonball boss, the surprise of finally riding in an eggpod, to the sky going dark after defeating the triple stage boss, the split second descent of this evil looking machine and thinking "what the fuck was that!!??" as you wonder where the fuck it will surface - as THAT music starts to play. GAH! The whole setup was akin to a fucking horror movie. Big Arm (or Squeeze Tag as it was called back then) gave me my only Sonic related knightmares. Death Egg Robo was awesome and runs it pretty close, but both of them shit all over Doomsday which doesn't even come close.