Hands down, Rosenclowns Lex is far more frightening. As great as Spacey is, his version is written poorly, his actions are moronic at times and why does he need a miss T. rip off?
Rosey's Lex is smart, manipulative, ruthless and is a better, more up to date version of Lex Luthor.
Spacey coould have been better, but he suffers from some mad scientist scheme in the movie. Wrong direction to take him.