A large bag suits anyone who actually carries things around with them all day, work, kids, gym kit, a change of shoes, rather than just a phone and a card. If you're someone who likes to travel light, or who already struggles with shoulder or back twinges, I'd think twice before going big just because it looks good on the arm in the shop. An oversized bag you're not filling properly tends to slump and swing about in a way that looks more like a chore than an accessory, and a heavy one with the wrong strap will tell you about it by mid afternoon.
Where a large bag comes unstuck is when it's paired with anything else that wants attention near the shoulder, a fussy coat with its own big collar or lapels, or a scarf wound up high, because the bag ends up fighting for the same bit of real estate and everything looks crowded. It works much better against something plainer up top. On quality, the difference between a bag that lasts and one that lets you down usually isn't visible from across the shop, it's in the handling. Pick it up properly, hold the full weight of it, not just a gentle lift, because a strap that feels fine empty can dig in once there's a laptop and a water bottle inside. Run a finger along the seams and check they're even, not puckered, and look at the base, which takes the most wear and is where a flimsy bag loses its shape first. Press on it gently to see if it's reinforced or just lining. Hardware matters more than it gets credit for, a zip that catches the lining as you pull it is one you'll be swearing at within a month, and clasps that feel light or hollow in the hand tend to loosen with use. Check the stitching around the strap attachments too, that's the point of failure on almost every bag I've ever worn out.
Before you buy, open every pocket and compartment and actually put your hand in, because photographs flatter interior space and some of these bags are far shallower than they look. Check the lining for loose threads, and if there's a long strap, adjust it fully to see it doesn't flop about or look like an afterthought.
Given a few months of real use, a well made large bag softens at the corners, the leather or canvas takes on a shape that's yours rather than the shop's, and the base darkens slightly where your hand rests on it. That's not wear and tear, that's just it becoming the bag you actually reach for.