In principle, I like [name]Michaela[/name] the best. It’s the classic spelling, and once you understand, I think it’s pretty easy to remember that it’s mih-[name]KAY[/name]-lah, not MY-kuh-lah or whatever. When I first saw [name]Michaella[/name], I thought it was [name]Michael[/name]-uh and quite hideous, actually, lol, but as soon as I knew, it made so much more sense.
I probably wouldn’t use any form of it since it’s quite overused (or, at least, it was several years ago! It seems like everybody and their sister had a [name]Michaela[/name] in Pennsylvania about 5 years ago!), but I do like [name]McKayla[/name]. In principle, I want to hate it (the Mc prefix denotes “son of”, and [name]McKayla[/name] is so much trendier, etc.), but I can’t help but think it looks so much cooler than [name]Michaela[/name]. [name]One[/name] of those two would get my vote, although I would never promote [name]McKayla[/name], haha, it’s just so trendy that way. For someone else, I would suggest [name]Michaela[/name], 100%.