Whether it's Lex Luthor fighting Batman in Rules of Engagement or Deathstroke fighting Green Arrow in Arrow, switching things up with the rogues of other heroes is a fun way to bring in fresh and innovative stories that haven't been done before
The fact that being the last son of Krypton burdens Superman with an unbearable loneliness but also imbues him with an almost selfish sense of pride makes his character so complex and interesting