I know there are some people here that know about this show. I didn't grow up with it myself, it ended when I was too young to even have a conscious memory.
My brother knew about this show though, so I looked it up because I remember liking Duck Tales when I was young as well, so I wanted to find out about this show. I saw a few episodes on youtube and I got hooked!
My favorite characters would have to be:
NegaDuck-he's PURELY evil, if you can even say "pure" and "evil" in one sentence. He's Darkwing's insane, twisted, violence loving evil twin. But I love this guy anyway.

Morgana-She's DW's GF. She is relatively kind and caring, but she was once a villain herself. She is also a witch, who can cast spells and those sort of things. She's a good witch though.
Gosalyn-She's DW's adopted daughter. She's full of personality and is very fiery. In other words, she's a tomboy.
Edit: Scratch what I said about it ending before I even had a conscious memory...I actually had somewhat of a memory, just not really...