Both Lana and Chloe overstayed their welcome on Smallville. I don't feel Kristen was miscast she was just misused. They had no idea what to do with her but wouldn't write her out because she was so pretty.
Henry Cavill is Superman/Clark Kent
Stana Katic, Natalie Dormer, Scarlet Johansson or Rachel McAdams for Lois Lane
Ben Affleck is Batman/Bruce Wayne