All four are good options but [name_m]Cassian[/name_m] and [name_m]Spencer[/name_m] are my personal favourites 
[name_f][/name_f] [name_m]Cassian[/name_m] is cool and fresh, but also well established; [name_m]Spencer[/name_m] is stylish but gentle.
Inspired by those, my suggestions would be [name_m]Adrian[/name_m], [name_m]Albie[/name_m], [name_m]Parker[/name_m], [name_m]Elliott[/name_m], [name_m]Rowan[/name_m], [name_m]Elias[/name_m], [name_m]Ivan[/name_m], [name_m]Evander[/name_m], [name_m]Finley[/name_m], and [name_m]Casper[/name_m]