As above - which of the three do you prefer? We already have a daughter [name_f]Mila[/name_f] and son [name_m]Cato[/name_m].
Those are all great names (including your current son and daughter’s names!). [name_f]My[/name_f] favorite is [name_u]Aspen[/name_u].
[name_f]Mila[/name_f], [name_m]Cato[/name_m] and [name_u]Aspen[/name_u]… So great!!!
[name_m]Atticus[/name_m]! I love the name [name_m]Atticus[/name_m]
Whoops, double post that doesn’t seem to want to delete…
I have a major soft-spot for [name_m]Atlas[/name_m] and would consider using it in a middle name place myself. [name_m]Atticus[/name_m] has wonderful literary connotations. I don’t much care for [name_u]Aspen[/name_u].
[name_f]Mila[/name_f], [name_m]Cato[/name_m], and [name_m]Atlas[/name_m] is a wonderful sibset 
I’ve always love [name_m]Atlas[/name_m] with your sibling set. I don’t believe we have a very similar style, but I swoon whenever I see it in your list. It goes perfectly with both [name_f]Mila[/name_f] and [name_m]Cato[/name_m]. 
Oh man, your kids’ names are soo cool! Loving [name_u]Arden[/name_u] paired with [name_f]Mila[/name_f] and [name_m]Cato[/name_m] is now officially going on my boys’ list, haha. I love [name_m]Atlas[/name_m] and also like [name_m]Atticus[/name_m] a lot. [name_u]Aspen[/name_u] is cool too, just not my favorite.
I vote [name_m]Atlas[/name_m], too!
I vote for [name_m]Atticus[/name_m]. such a cool name! I like [name_m]Atlas[/name_m] and am not a fan of [name_u]Aspen[/name_u].
Another vote for [name_m]Atlas[/name_m] here!
[name_f]My[/name_f] personal favorite of the three is [name_m]Atlas[/name_m].
But I think [name_f]Mila[/name_f], [name_m]Cato[/name_m], and [name_m]Atticus[/name_m] sounds best.
[name_m]Atlas[/name_m] and [name_m]Atticus[/name_m] are my two favourites from the three
I agree that [name_f]Mila[/name_f], [name_m]Cato[/name_m] and [name_m]Atticus[/name_m] sounds best, but I also love [name_u]Aspen[/name_u]. I think [name_m]Atlas[/name_m] sounds too wordy here
I [name_u]LOVE[/name_u] [name_m]Atticus[/name_m], it sounds so wise yet trendy x
Hmm, looks pretty close between [name_m]Atticus[/name_m] and [name_m]Atlas[/name_m]. I worry that [name_m]Atticus[/name_m] is getting too trendy, although I don’t actually know any in real life.
[name_m]Atlas[/name_m] for me because I think it is both more unusual and easier for a smal child to say and spell and there is no need to shorten it and it fits really great with the other names
Beautifully named children already.
I love [name_f]Mila[/name_f], [name_m]Cato[/name_m] and [name_u]Aspen[/name_u]!
[name_m]Don[/name_m]'t mind [name_m]Atlas[/name_m], but lean to [name_u]Aspen[/name_u] as feel it has slightly more positive meaning. [name_u]Aspen[/name_u] could gets Azza or [name_u]Pen[/name_u] as nicknames vs [name_f]Atty[/name_f] is the only thing I can think of for [name_m]Atlas[/name_m] - not sure if any of these grab or offend you either way? Or whether either [name_u]Aspen[/name_u] or [name_m]Atlas[/name_m] flows better with your thoughts for middle names.
[name_m]Atticus[/name_m] is a very beautiful name, but I think the others make for a nicer sibset with your other children, and in general is more cumbersome so maybe better suited to a middle name?
All beautiful options though with no obvious negatives - so don’t think you can go wrong
I love [name_m]Atlas[/name_m]! I agree with the reply above that [name_m]Atticus[/name_m] is rather cumbersome. [name_u]Aspen[/name_u] is a nice name but I’d rather see it on a girl. [name_m]Atlas[/name_m] is a great name; strong and unusual without being too out there.