I've always used the term "likable" to refer to characters that are either sympathetic or cool/interesting. . .

Likable does not mean simple, devoid of conflict, or lacking flaws. It means characters that we give a damn about. If the reader doesn't care what happens to your characters, then you'd better be working real hard to keep them invested in other ways. And that's tough. All over the place I see people talking about how characters are more important than plot. Not many authors are up to the task of writing a plot that can keep people hooked despite not caring about the characters.