I much prefer the Alto Sabrina to the Alto Camilla, for a number of reasons. While the larger Camilla is a beautiful bag, I do find it large. Also, aside from the center zip compartment, the top of the bag is largely open. The tab that keeps it closed is a pain to deal with. And because the leather is thick and structured, the sides are open at the top. The handle structure is also a bit strange.
The Sabrina is a generous medium sized handbag, with a wide base, and very user friendly. It has a top zip and the size and style just work well. I love the Sabrina.
The Florentine Bristol is my favorite Florentine style. I love the shape, the top zip, and the leather.
Choosing between the Sabrina and the Bristol is difficult, because the leathers are so different. I don't think either is overly heavy, and I'm sensitive to handbag weights. But Florentine leather is probably heavier than Alto, and also the Bristol has extra leather trim in the belting, that adds to the weight.
I'd say to make the choice based upon the kind of leather and handbag style you prefer.... structured in the Sabrina or softer (but not slouchy) in the Bristol. Colors might also be a factor, as the Bristol is only available in limited colors. Scratches might buff out in Florentine, they won't in Alto.