I was having this exact same question in my mind today as I see both bags at SCP chanel.....the black was available for me to buy if I wish and the bronze is someone else's bag (I am down on the list)....The SA 1st showed me the black one, and I thought, nice but this bag in black is like "just another big black bag." Doesn't stand out, doesn't give me that "wow" feeling.
Then the SA shows me the bronze one she's holding for someone, and I was like "wow, I do like the bronze more, not too shiny, looks almost like brown but it stands out in the crowd." Since it is not a shiny metallic bag it actually goes with lots of colors, just like a brown color bag.
Another thing is personally I am not too into the distressed leather, on the other hand, the bronze one has a subtle metallic sheen on it. Such a unique color yet it is not tacky or cheesy or too much. Def. love the bronze more! By the way, this exact same bronze color/leather is also used in the newest lux bags. I also tried on the new bronze lux flap today, real nice.