Here's an off-the-wall opinion that I've held fairly strongly for a long time.

Not nearly enough jackets out there have, what do they call it, a two-zipper system. I don't know the proper name, but where the jacket has two zippers, one that you can use to zip it up, but then another one that can then be used from the bottom to unzip it partially. This becomes especially useful when you need to sit down when wearing the jacket, so that it doesn't bunch up around your hips or waist when you sit. Being able to unzip it partially allows for it to loosen and open at the bottom, which is really nice for when you're sitting.