Tough call - esthetically, I like the look of the First better in such a bright color, and the shape appeals to me more. But my only Bbag is a City! I need the space - big enough to hold papers, water bottles, etc...
What are your needs? A red first would be great for light errands or a night out, but anything more than that, I'd go for the City.
I wouldn't be surprised that the Rouge Vif is more popular in the First... my local store only orders the more neutral colors in the City since that's what most people want... outside tPF that is!!