NO character should be killed off!
A character is only as good as the writer giving them the voice.

Perfect example - Booster Gold
Written by Jurgens or Johns? A great, multilayered FUN character portraying an image to the world to hide the true heroism he performs in secret.
Written by King? An incompetent moron.

I'd argue there are no BAD characters, just some who hasn't found the right creator the lend them the voice that resonates.