"Which bit is the harshest" relies on so many different variables it's not even funny. It depends on how the bit is adjusted, how it's used, what horse you're using it on, who's holding the reins....most bits, however horrible they look, can actually be valuable, humane tools in the right hands. That said, it's hard to justify bits such as these:
Who needs that much leverage, particularly with a pinching mouthpiece?
A cathedral port is really a bit much.
A spade bit is downright cruel and abusive on any horse not properly trained in the vaquero tradition....and few are.