I really like both! they're adorable, and unlike some names, they'd suit a little girl and a grown woman. For instance, the name "Millie" is cute on a 5 year old, but can you imagine a grown woman called Millie?
I really love the spelling, its a really unique contrast to "Leyla" and "Lila" and i think it looks really classy :)
Middle name i think will suit both are:
Leila/Laila Grace (Kate Moss's little girl is called Lila Grace)
I think any one syllable name would flow nicely actually, there's loooads!
I really love both Leilah and Laila, but Laila is probably my favourite (just)
Congrats on your baby, and Good Luck! xx