The first properly cool morning in September is when a sports jacket earns its spot by the door, the kind of day where a coat is too much and a plain jumper isn't quite enough, and you want something with a zip you can pull right up on the walk to the car.
It doesn't sit well next to anything too polished. Put one over a crisp shirt and tailored trousers and it looks like you got changed halfway through the morning and gave up, and the same goes for proper gym kit underneath, all that technical fabric peeking out at the collar makes the jacket look like an afterthought rather than a choice. It wants something plainer doing the supporting work, a cotton tee, a jumper with no fuss on it, jeans rather than anything pressed. Where it genuinely lets you down is anywhere you need to look like you tried, meetings, anything with a dress code, actual bad weather. The fabric on most of these is showerproof at best, and I've been caught out more than once thinking a soft shell jacket would see me through a proper downpour, it does not, it just gets heavy and cold and clings. It's also not warm on its own past about October here, you need a jumper under it or it's decorative.
The ones I keep reaching for are navy, a soft bottle green, or that grey that isn't quite charcoal and isn't quite silver, because they don't fight with anything else you own and they don't date the way a bold colourblock panel does after one season. Avoid anything with a shiny finish unless you actually like looking like you're about to do a parkrun, a matte or slightly brushed surface wears far better day to day and doesn't shout. Before you buy, check the zip pull is metal or at least solid feeling rather than a thin plastic tab that snaps the third time you're rushing, check the cuffs are ribbed and have a bit of stretch rather than a floppy elastic that goes slack within weeks, and have a feel of the lining, a mesh lining breathes better than you'd expect and stops the jacket sticking to a jumper when you take it off indoors.
Tomorrow I'd wear mine over a plain white tee with straight leg jeans and old trainers, nothing clever, just something that moves when I do.