Short list I am considering:
[name_m]Samuel[/name_m] ([name_u]Sam[/name_u])
[name_u]Luca[/name_u]
[name_m]Henry[/name_m]
Middle name will be [name_m]David[/name_m], and last name is a hyphenation of two monosyllabic surnames.
Looking to expand our list of possibles as well as hear opinions on our shortlist!
We aren’t averse to common names, but do want to avoid trendy (example from my generation: [name_f]Elizabeth[/name_f] is fine, [name_f]Tiffany[/name_f] is not).
Thanks!
I’m liking [name_u]Luca[/name_u] and [name_m]Henry[/name_m] from your list!!
A few more suggestions
[name_m]Isaac[/name_m]
[name_m]Benjamin[/name_m]
[name_m]Leon[/name_m]
[name_u]Finley[/name_u]
[name_m]Lewis[/name_m]
[name_u]Rory[/name_u]
My favourite on your list is [name_m]Samuel[/name_m] ([name_u]Sam[/name_u]) which is a perfect choice as a brother to [name_m]Oscar[/name_m] [name_f]IMO[/name_f]. The first name that came to mind reading your post title was [name_m]Reuben[/name_m].
My favourite is [name_m]Samuel[/name_m] ([name_u]Sam[/name_u]), I think it fits very well with [name_m]Oscar[/name_m]. Other names that came to mind: [name_m]Tobias[/name_m], [name_m]Felix[/name_m], [name_m]Angus[/name_m] and [name_m]Damien[/name_m]. I also like the suggestion of [name_m]Reuben[/name_m].
[name_m]Hi[/name_m] there.
I love [name_m]Oscar[/name_m]! It’s quirky yet classic, and I think grows up well.
Here are my thoughts on your short list:
[name_m]Samuel[/name_m]-I love this name. It’s gentle sounding, yet strong at the same time. It isn’t super overly popular, and certainly classic. Great with [name_m]Oscar[/name_m] too.
[name_u]Luca[/name_u]-This is another one of my favorites. I think it’s cute with [name_m]Oscar[/name_m]. Maybe would be a little odd if there’s not Italian in the family. That’s just knit-picking. [name_u]Luca[/name_u] seems very artsy to me, and I like that it’s not heard that often.
[name_m]Henry[/name_m]-Great name, but there are so so many of them. [name_f]Do[/name_f] you like the nn [name_m]Hank[/name_m]? That’s my favorite part of [name_m]Henry[/name_m], and that would help him to stand out. [name_m]Oscar[/name_m] & [name_m]Hank[/name_m] would be adorable.
Here are some suggestions:
[name_m]Alec[/name_m]
[name_m]Adrian[/name_m]
[name_m]Bennett[/name_m]
[name_m]Charles[/name_m] nn [name_u]Charlie[/name_u]
[name_m]Calvin[/name_m] nn [name_u]Cal[/name_u]
[name_m]Eli[/name_m]
[name_m]George[/name_m]
[name_u]Ira[/name_u]
[name_m]Ivan[/name_m]
[name_m]Jacob[/name_m] nn [name_m]Jaco[/name_m]
[name_u]Max[/name_u]…maybe [name_m]Maxwell[/name_m] or [name_m]Maximus[/name_m]
[name_u]Nico[/name_u]
[name_m]Nicolas[/name_m] nn [name_u]Nico[/name_u]
[name_u]Rafe[/name_u]
[name_m]Simon[/name_m]
[name_m]Theodore[/name_m] nn [name_u]Theo[/name_u] or [name_u]Teddy[/name_u]
[name_m]Vincent[/name_m]
[name_f]Hope[/name_f] this helps. 
I would choose something familiar but a little more offbeat like [name_m]Oscar[/name_m]. [name_u]Luca[/name_u] is my favorite from your shortlist.
[name_u]Seth[/name_u]
[name_m]Quentin[/name_m]
[name_m]Gregory[/name_m]
[name_m]Philip[/name_m]
[name_u]Asa[/name_u]
[name_m]Vincent[/name_m]
[name_m]Simon[/name_m]
[name_m]Wesley[/name_m]
[name_m]Zane[/name_m]
[name_m]Ambrose[/name_m]
[name_u]Blaise[/name_u]
[name_m]Peter[/name_m]
[name_u]Leland[/name_u]
[name_u]Nico[/name_u]
[name_m]Killian[/name_m]
[name_m]Leon[/name_m]
[name_m]Frederick[/name_m]
[name_m]Hector[/name_m]
I really like [name_m]Henry[/name_m] with [name_m]Oscar[/name_m]. [name_m]Samuel[/name_m] is a good choice too.
[name_m]Simon[/name_m]
[name_m]Thomas[/name_m]
[name_m]Gordon[/name_m]
[name_m]Adam[/name_m]
[name_m]Patrick[/name_m]
[name_m]Linus[/name_m]
[name_m]Edmund[/name_m]
[name_m]Warren[/name_m]
[name_m]Rufus[/name_m]
[name_m]Charles[/name_m]
I like [name_m]Henry[/name_m] with [name_m]Oscar[/name_m]!
Other suggestions: (* for my favorites)
[name_m]Tobias[/name_m]
[name_m]Theodore[/name_m]
[name_m]Thomas[/name_m]
[name_m]Isaac[/name_m]*
[name_m]Evander[/name_m]
[name_m]Nathaniel[/name_m]
[name_m]Sebastian[/name_m]
[name_u]Love[/name_u] [name_m]Samuel[/name_m] with [name_m]Oscar[/name_m]!
I will echo the love for [name_m]Oscar[/name_m] and [name_u]Sam[/name_u]/[name_m]Samuel[/name_m] as brothers. I also really like [name_m]Leo[/name_m] as a choice!
[name_m]Henry[/name_m] is my favourite from your list - both in a combination with [name_m]David[/name_m] and as a brother to [name_m]Oscar[/name_m]. [name_m]Samuel[/name_m] comes up second. [name_u]Luca[/name_u] feels quite stylistically different to [name_m]Oscar[/name_m] for me, but I do think it’s lovely.
[name_m]Felix[/name_m] was my first thought - so I second that. I’m also seconding [name_m]Leo[/name_m]/[name_m]Leon[/name_m] for the subtle animal connection (“deer-lover” and “lion”), but also because I think they work really well together.
I think [name_m]Oscar[/name_m]'s brother is [name_m]Wilbur[/name_m]
I love [name_m]Samuel[/name_m]!