Dukat's like a comic book villain. No matter how many times you beat him, no matter how far down he goes, he manages to come back to threaten the good guys, usually becoming more crazy in the process. There's still a lot more crazy in him if you're only part of the way through the ending episode arc.
Damar... I don't want to spoil anything, but a lot of his problems will come to a head soon. Not to mention he has what I think is the most hilarious moment in Trek, maybe you've already seen it but the line about talking to Worf again.