I definitely think Gerard Darel bags are classic.
Their shape is really simple, the leather is gorgeous and they age really well (I bought my first one in 2007 and the leather is TDF, even more beautiful than some really expansive bags...) However, it is true that when placed down they tend to expand but if you chose a 24h with pockets (I think it's this one you're referring to) it's not so bad, they still keep their shape (I have 2 24h with pockets and a simple one and the difference is quite big)
Hope this helps!