I have always know Leila to be pronounced Lay-la. DD2 has a Leila (Layla) in her swimming class. At work we have had a couple of Leila's come through and both have pronounced it Layla.
I do think Leila looks better than Leela, but if that's how you want it pronounced then perhaps you are best off spelling it Leela.
I'm not sure how else you could spell it - Leelar, Leelah, Leighla, Leighlar, Leighlar all look a bit awkward!
I like the sound of Leela, just not sure how you'd spell it. But if you don't mind correcting people all the time then go with Leila!