I do like it (prefer
Emmeline which seems "right"), however, if popularity is a concern of yours, then there's nothing to really distinguish
Emeline from
Emily,
Emilia or
Emma since they could all have the same potential nns (
Emmy,
Em). This sort of reminds me of one of my faves,
Gemma. While it doesn't begin with an E, it rhymes with
Emma and it makes me wonder if it would come across as an
Emma alternative (and a not very creative one at that). That's probably why I'd never use it.