Thanks for the feedback!
I edited my OP to make clear I'm excluding surnames - in any case,
Avery (a form of
Alfred),
Addison (son of
Adam) and
Casey (from an old Gaelic name) all strike me as traditionally masculine names.
Dana is a good example but I'm looking for English names only - likewise,
Joan is a male Catalan name but I don't consider the English name
Joan unisex.
Dakota is a good suggestion, though!