Longer in the back, longer in the sleeves. Being able to securely tighten the sleeves over gloves is really nice. I find that long enough (in the torso) zippered jackets often are pretty long in the front, and unless the zipper is pretty lightweight (or it's an anorak and the zipper doesn't go down all the way) it tends to bunch uncomfortably when riding on the drops. Find a zipper that's both durable and flexible?

Also, zipper pulls that won't break and are glove-compatible, and pocket linings that won't get hung up on gloves. There is nothing worse than having to take your gloves off all the time in the cold.