The fleece hoodie has a reputation for being the thing you wear when you've given up for the day, and I think that's unfair. A good one is doing exactly what it's meant to, which is keep you warm without any fuss, and there's no shame in that.
Sizing is where most people get caught out, because fleece has give in it that cotton jersey doesn't, so a size that feels right in the shop can end up loose and a bit shapeless by the end of the day. I've learned to go for my usual size rather than sizing up out of habit, and to check the shoulder seam specifically, because if that sits halfway down your arm the whole thing reads as borrowed rather than chosen. On me the sleeve length matters more than most people would guess, since a lot of fleece hoodies are cut generously everywhere except the arm, and I've had more than one that stopped a good two inches above my wrist bone, which is fine for leaning on a desk and useless for anything outdoors. Length at the hem is worth checking too, standing up and sitting down, because fleece can ride up in a way that thinner fabrics don't.
For actual wearing, it goes with things you probably already own rather than anything you'd need to buy to match it. Straight leg jeans and trainers, under a plain parka for the school run or the dog walk, over leggings for travelling, with joggers for the version of the weekend where nobody's expecting you anywhere. It layers well under a denim jacket too, which surprised me the first time, because I'd always thought of fleece as the outer layer rather than something tucked under one.
In the shop, before you buy, check the inside of the hood lining, since cheap ones use a thinner fleece there that pills within a few washes, and have a proper look at the zip if there is one, pulling it right to the top and down again, because a zip that snags halfway is a daily irritation you'll feel every single morning. Run your hand over the main fabric too. A well made fleece hoodie has a density to it, a bit of weight, and doesn't flatten under your palm the way the thin ones do. The cuffs and hem should have proper ribbing with some recovery, not ribbing that's already gone slack on the hanger.
What it won't do is look polished. It isn't trying to, and if you need something to do that job, this isn't it.