I've never really thought about
Flann before, but I think it could grow on me, especially as a nickname for
Flannery or
Flannan. The meaning of the name is somewhat close to the feeling I take from it --
Flann makes me think of a warm fireplace and a hearty meal. The one thing holding me back at the moment is pronunciation. I'd always pronounced it as "flawn" (like fawn), but I now see it's more like "fan". It doesn't sound as attractive.
Not a fan of
Ennis on either gender, though I'm usually fond of -is girls' names. Something about it sounds vaguely medical or biological.