I have the 25 in Azur and the 30 in Ebone Damier and that's the way I like 'em. The 25 holds a lot more than it looks like it would and keeps its shape better. I tend to carry the 25 when I don't need everything and the 30 when I'm traveling or on days when I'm carrying extra stuff or gloves/scarf etc. If you can only have one I say go for the 30. Better to have too much than not enough.