The students are a bunch of talented high-schoolers, however they only picked up programming this September. That means good tooling and a friendly compiler are paramount, because they'll often be leaning on both.
I don't have experience with any of the languages, but I write Haskell and Typescript for living, so I should be able pick these up rather quickly. Because I know Haskell so well, I lean towards PureScript, but I don't want to base my decision only on this.