I’m a non-binary Quint who goes by “Quincy”! 
(so maybe a bit biased! 
)
I think of Quincy as a primarily (but not exclusively) masculine name and of Quinn as more “true neutral” to feminine (mainly because of the increasing usage for girls).
I’ve always really liked the name Quincy because it has a vintage and posh feeling to it while also feeling fun and quirky!
The combination Quincy Sunday is so spunky and adorable (bouncy is the PERFECT word for it)! Personally I love the matchy ‘y’ ending! I could definitely see it on a little girl 