Both are beautiful. But I prefer Colombe by far. Colombe is the name of a deep-thinker, someone who is calm, elegant and wise. Victoire has more of a show-off feeling to it; it's flashier. She's extremely intelligent, but then again so is Colombe.
I prefer Colombe.Victoire: harsh, strange and aloof. Colombe: mysterious, having artistic tendencies, but also a bit strange. Definitely more feminine and accessible than Victoire.
Victoire or else...Colombe sounds way too "heavy" and male for a girl, in my opinion. Go by Victoire which is nicer. I prefer Victorine, though. It sounds more female.
Victoire - more familiar to non-Gallic eyes. I saw a Colombe on a British news channel recently, though, reporting from Paris with a sexy French accent. She was very stylish.