I like Whitney's, but Amy captured the darkness of the song really well. Whitney's is an interesting, bittersweet take and the dance-y production is really different for the song but she sounds kind of Breathless even on record, especially in the beginning. The production on Amy's is nice and I prefer Amy's vocals, even if she mumbles throughout half of it.
Sad thing is, they both covered it really recently before their deaths too, eerie.