Well, actually, yes there is a
Kaufmann translation.
The only version of Zarathustra I've read is the Kaufmann translation in
The Portable Nietzsche, so I don't really have much basis for comparison. I haven't really read much of Nietzsche that wasn't Kaufmann in general. I also find his commentary insightful, but maybe I should look into some other translations at some point - though frankly I'd almost rather just learn German and read the original stuff.
So. I can't speak from experience on
Thomas Common and
R. J. Hollingdale, but it looks like either of them should be okay. Personally I'd recommend Hollingdale because he did his work post-WW2, worked with Kaufmann, and helped restore Nietzsche's image. A quick google reveals little about Common, but I know the early translations were plagued by input from Nietzsche's sister, a raging anti-Semite. I don't know how much that would be reflected in Common's Zarathustra translation, but I would prefer the more recent version just to be safe. Also it would probably have more extensive commentary and more modern language.