I was in the same boat a year ago and I opted for the cabas. I shared your concerns about wanting a "forever" bag--therefore leaning toward the cerf, but really liking the cabas more. I don't regret my choice a year later. For one thing, the cerf didn't fit me as well. The strap didn't go over my shoulder, while the cabas looked good on the arm and shoulder. And, I think the cabas has enough elements of traditional Chanel and an understated elegance that will help it stand the test of time.