The roughest rollercoaster I have ever ridden would have to be Thunderbolt at Dreamworld on The Gold Coast , Australia it absolutely bashed my head from one side to the other I had a stuffed neck etc for weeks after riding it. I can't say I was disappointed when it was demolished. Probably caused people serious injuries it was so bad.
Flashback at Magic Mountain in CA was quite rough from what I can remember of my trip there.