Kathleen is nice. I find it somewhat dated but it sure beats
Caitlin at the moment. It could definitely make a comeback. I haven't known many Kathleens at all (about a handful). The oldest is about 60, the youngest is 18.
Between
Kathleen and
Cathleen, I prefer
Kathleen.
Cathleen just looks wrong to me even though I know it's not. Overall, I prefer
Katherine. The sound of
Kathlyn / Cathlyn doesn't appeal much.