And now we come to arguably the greatest (and indisputably my favorite) live-action Lex Luthor of them yet:
Lex Luthor VI - Michael Rosenbaum (SMALLVILLE tv show)
He was Lex Luthor full-time from the first seven seasons of SMALLVILLE and then reappeared 3 seasons later for the final episode. From Fall 2001 - Spring 2008, and then again for the series finale episode in Spring 2011, he put out a much deeper, much more emotional Luthor than had ever been seen before (or since). No one has put in more screentime as Luthor than Rosenbaum.