For years I bought my hoodies one size up and called that oversized, then wondered why I looked like I'd borrowed something that still fit me properly. The actual version, the one with dropped shoulders and sleeves that swallow your hands, is a different shape entirely, and once I tried a genuine one on I couldn't go back to the fitted kind for anything other than the gym.
The good ones get softer with wear, not thinner, which is the distinction that matters. A heavy cotton or cotton blend will feel a bit stiff across the chest for the first few washes, almost cardboard-ish, and then it gives in and starts to mould to how you actually stand and sit, which with a hoodie usually means slumped. Wash it inside out, cold where you can, and skip the tumble dryer unless you fancy a jumper that fits a ten year old by autumn. Mine lives on a low heat setting on the radiator and has done for two winters without the cuffs going stringy. The drawstring is always the first thing to let you down, so if you can find one with metal tips rather than plastic, that's the detail that tells you someone thought about it past the photograph.
Where it earns its spot is in how little it asks of anything else. Leggings and the hood up, that's the school run. Straight leg jeans and trainers with the sleeves pushed up, that's meeting a friend for coffee and still looking like you tried. I've worn mine over a slip dress on a cold evening, which sounds like a fashion crime and looked, oddly, like I knew what I was doing. It sits well over a long sleeve top too, which matters more than people admit once the weather turns properly grim. Autumn through to the start of spring is really its season, though I'll wear one in a thin cotton on a cool August evening without a second thought, the oversized cut keeps air moving in a way a fitted one never does.
What changes over time is the collar mostly, it loosens slightly and sits a little lower, and the fabric at the elbows thins before anywhere else does, which is just where you lean on things. Neither of those is a fault, to be honest, it's just the hoodie learning your shape. The colour fades a touch if you wash it too often in anything warm, going from a proper black to that charcoal that every old hoodie eventually becomes. By the time it's properly broken in, it's usually the one you reach for without thinking, and the one you'd be genuinely annoyed to lose.