Lex's "stupid costume" line was perfect. It feels like just from a few lines, Hoult already feels like the perfect Lex Luthor, with a clear objective. I feel like Eisenberg's--I can't even call him Lex Luthor--but Eisenberg's lunatic-Lex's motivations seemed complicated, moreover unclear. You could debate about it if you want, but his motivations didn't seem believable, nor made any sense to me. It just seemed flat-out too complicated and ridiculous.
There have been bad interpretations of comic book villains, and good ones. I think Luthor in Superman Returns was dull. His performance at times was entertaining, but still didn't seem that good of a villain. His hatred for Superman didn't seem clear enough. But the real estate plot...what do you start with, what resources for food and other things you need in life after you wipe out Earth's land with a green fortress and some crystals? Couldn't understand that.
Say what you want about Superman IV, as bad as it was, Gene Hackman was extremely entertaining in the movie. He seemed more evil than his performance in the first Superman movie, where he came across as more goofy than villain-like. While he was funny, he didn't seem like much of a threat. He seemed to like Superman in spite of trying to kill him.
But his lines such as, "The-end-of-Super-man" and "Destroy Superman" in Superman IV were some definitive moments of the character.
I think there are various traits that define a villain or there is at least one trait that makes them great. Eisenberg was not one of them.