I love the City but the First is my all time favourite BBag style. It's the first style I ever got in the way of a designer bag and I like the look of it better.
Actually, I don't like the City that much.... I LOVE the Day a lot lot more! And it was the shape that was the most flattering on me! Closely followed by the First, which I never thought would look good on me based on seeing pictures, but IRL was an entirely different story. The Twiggy/Work I like too!
Sorry I couldn't pick because I like the day and the twiggy pretty much the same. I think the twiggy can be more easily dressed up the day is a very casual bag so I think they do serve diffrent purposes.