Nathaniel
Lovely but now very popular along with Nathan
Lucian / Lucien (how would you pronounce these also?
I love it - Lucian is the UK spelling (Lucien is French) - it’s LOO-see-un (LOO-see-en is French, you sometimes get the feminine form Lucienne in the UK)
Barnaby
I like it although I prefer Barnabas. You have to be OK with Barney as a short form though.
Tobias (but not Toby)
I like it but there is a high chance he’ll be Toby day to day, so don’t do it if you don’t like that.
Jeremiah
Quite nice although much prefer Jerome.
He’s very unlikely to be call Jeremiah day to day, it’ll get shortened. if you like Zachariah, Zach is better than Jerry
Lucas
Nice but getting very overused along with Luca. Linus is nice, or plain solid Luke.
Jonty
It’s cute, but too nursery posh for a full name - call him Jonathan or John on the birth cert, he really may not want to be Jonty when he’s older.