For sheer terror factor, Takabisha at Fuji-Q Highland in Fujiyoshida, Japan, claims the title. Opened in 2011, this Gerstlauer Euro-Fighter holds the Guinness record for steepest drop: 121° (beyond vertical).
Honorable mentions: Kingda Ka (tallest/fastest), Steel Vengeance (best hybrid), X2 (4D spinning). But for psychological intensity, Takabisha's "falling forward into nothing" moment is unmatched.