Vivien hands down. [name_u]Collins[/name_u] sounds so awful to me, far too masculine.
Either works! I say go with your gut!
It’s worth bearing in mind that [name_u]Collins[/name_u] seems a bit strange to some people outside of [name_u]America[/name_u]. To many it’s completely unfamiliar, so you might get some harsh feedback about it. [name_m]Don[/name_m]’t be discouraged, it’s a sweet name!
I prefer [name_u]Collins[/name_u]! So cool for a girl. [name_u]Collins[/name_u] [name_u]Vivien[/name_u] maybe?