Mitch is a nightmare, but Grimes is much younger. We have seen how difficult it is to dislodge ANY senator. It is better for Mitch to be reelected as he is 72 and may not last through the next election. Grimes is less than half that age (35) and could be the next Robert Byrd. She could spend the next fifty years doing untold damage to the Republic.
This is likely McConnell’s last term. He also has his faction, but there’s not a “McConnell dynasty.”
Grimes, while personally younger, is part of a political establishment even older than McConnell’s...one that has been weakening, but if they get into a U.S. Senate seat, they will be stronger than ever for decades to come.