I love Bronte Caspian! 
Completely neutral for me. Surname names are generally fair game in terms of gender imho. And it means thunder which is very cool!
I was at school with a Brontë (g) before I knew the literary reference and remember thinking of it as a strange, edgy name for a girl (honestly most of the class called her Brontosaurus, that was our main association at the time 
).
This is gorgeous too!