I come to Kotlin from Swift (and Java of course). One minor syntax thing about Swift that I like better than Kotlin is the use of the ! after the type in var definitions instead of the ugly (IMO) “lateinit” keyword. (Swift calls the feature “Implicitly Unwrapped Optionals”.) I realize this is a breaking change, so it won’t happen soon, but maybe for version 2?
FWIW, in general, I like Kotlin much more than Swift. I appreciate the Kotlin designers reluctance to add features just for the sake of adding features. Keep up the good work.