Congratulations!
For me, [name]Brynn[/name] totters on that unisex line. It OUGHT to be good for a boy or a girl, but it just seems delicate and feminine, yet unfussy to me.
[name]Avery[/name]…is probably my second choice on your list. It just seems a bit too sturdy compared to [name]Brynn[/name].
[name]Aria[/name]…on the other hand, seems a bit fussy. I’m probably thinking about a soprano singing here.
[name]Isla[/name]…balances with [name]Brynn[/name] very nicely. My first choice.
[name]Kyla[/name]…I don’t care for…it just seems related to [name]Kayla[/name] and [name]Haylee[/name], and it seems to me that the time for those names is past.
[name]Aly[/name]…doesn’t seem like a full name to me.
[name]Bennett[/name]…is my brother-in-law’s name, and he’s very masculine, so I just can’t go there.
[name]Isla[/name] [name]Cecilia[/name] is my choice.
For the boys,
[name]Hudson[/name]…is a surname I like. Hud as a nn is pretty cool
[name]Easton[/name]…seems a little…I’m not sure…airy? next to [name]Brynn[/name]
[name]Grayson[/name]…and [name]Easton[/name]…are names that just seem like they are trying too hard to me. I’m not sure what I mean by that, because I don’t dislike the names on the surface.
[name]Cole[/name]…is unobjectionable to me, but doesn’t inspire me. Also I’m not sure I like “[name]Brynn[/name] and [name]Cole[/name]”…
[name]Jace[/name]…doesn’t sound complete. Might be a nice nickname for [name]Jason[/name] though.
[name]Bowen[/name]…as in [name]Owen[/name]? I sort of like this, but I think a lot of people will pronounce it as though the first syllable rhymes with ‘wow’.
Of these, [name]Bowen[/name] (though I prefer [name]Owen[/name]) and [name]Hudson[/name] would be my choices. Given your entire list, I would not use [name]Case[/name] as a middle–I’d opt for one of the more traditional names.
As for other suggestions:
For a boy I might choose a name rooted in [name]Wales[/name] that sounds very masculine and familiar. (I’m assuming you are in the U.S.):
[name]Morgan[/name]
[name]Owen[/name]
[name]Griffith[/name]
[name]Evan[/name]
[name]Rhys[/name] (or even [name]Reece[/name])
And (oh, why not?) going to the same source for girls–
[name]Gwyneth[/name]
[name]Carys[/name] (I love this)
[name]Nerys[/name]
[name]Tegan[/name]
[name]Rhonda[/name]
[name]Eleri[/name] (or, maybe, [name]Ellery[/name])
[name]Rhian[/name]
[name]Jenna[/name]
Before you went with a Welsh theme, though, you should be sure there are enough possibilities to cover subsequent children.