I would pronounce Leila as 'lay la' and I like Leila better, think it looks prettier. Plus, if you're going with Sayle, it depends on whether the name's too 'y'ish for you? But in all honesty that's coming from someone who only likes y's in names when they're the traditional spelling (eg. I'm not advocating for Eevonne or Anthonee).

It's a lovely sounding name though. What spelling are you leaning towards?