I don't have one, but I do think of purchasing either a vintage or something from the new collection.
the thing is if I wear a backpack it got to be a practical one and I haven't seen a chanel backpack that fit my criteria
The graffiti one, even though it's not leather, looks quite practical. Comes in different sizes and I've seen people post them decorated with chanel brooches they've collected. I love them, but don't need to carry that much stuff so can't justify purchasing one either.