Here's my list and reasons:
Howe - for having his soldiers kill children for what seems no reason. What a land dispute? Just cold and heartless, more so than Loghain.
Orsino - No matter what he says, what he preaches, he still gives in and uses some horrific blood magic at the end for again no gain. I mean at least Meredith had just cause with her Right of Annulment request.
Mage Warden - They can make deals with demons for children's lives, defile sacred 'ashes', help werewolves slaughter/turn an entire elvish clan, bring back a device that can is used by taking the souls of Dwarves and placing them into stone bodies to control, kill their 'friends'.
Quentin - murder of Leandra and other women to make a version of his woman and bring her back... more really evil just sadistic.
Solas - massive liar who cares little for his actions or the plight of others to fix his own mistakes.