Well, as someone who grew up with loads of girls with this name (and variant)...I'd have to say that I like
Makayla the most. It's the most common and the spelling makes pronouncing straightforward.
Mikayla is another common spelling I've seen, so I'll add that. I don't care much for
Michaela (the original), because I always want to say, "MY-kul-luh" (
Michael, with an A). I can also appreciate Macayla, because I love the name
Cayla. I'd definitely be mispronouncing a lot of these spellings...