For most cases it doesn't really matter. However if seas were rough then it is ironic that the cheapeast cabins (those on deck 2) ride better than the expensive cabins on deck 10. Cabins on the lowest deck and closest to the ships centerline have the least amount of felt motion.
But seas rough enough to make a noticeable difference in cabin ride are rare (at least to me), so I really wouldn't worry about it. I typically try to get a cabin close to the pool deck since I hang out there. I'd be more concerned with keeping in mind what is above and below my cabin - such as a running track or a lounge with live music. These can give you more of a problem than the motion of the ship.