I voted for Green, but that's just because I love green and there's definitely not enough green bags out there.
But, all of those four colors are great, in my opinion. Stone - is that a new color or is it just another name for Smoke? Either way, you can't go wrong with whichever one you choose.
What leather are they made of? Some seasonal colors are often calfskin, if I remember correctly. Lambskin and calfskin are quite different from each other. Lambskin is usually referred to as 'Luxe' leather on the PS tags.