You know a good modern fixture the second you flip the switch. No hum, no flicker while it warms up, just light where you want it and nowhere you don't. The best ones feel solid in the hand before they even go on the wall, a real weight to the metal, a dimmer that turns smooth instead of catching halfway through.
Over time this is where the cheap ones show themselves. A year in, a painted finish on a sconce can start wearing thin right where you touch it to turn it on, and a plastic diffuser yellows faster than anyone tells you it will, especially somewhere that gets afternoon sun. A good metal finish just dulls a little, softens, which honestly looks better than new after a while. Wipe it down with a dry cloth and skip anything wet near the base or the wiring, dust is really the only enemy here, and a light coat of it on a matte black fixture is the difference between fine and grim.
Where this goes wrong is when modern means delicate. Thin exposed bulbs, open wire cages, low hanging pendants, they look sharp in a house with high ceilings and no kids running through it, and they look like a trip to urgent care in a smaller place with a toddler and a dog that's still learning where the furniture is. I'd also think twice in a rental, since a lot of the better modern fixtures assume you're comfortable swapping out whatever ugly builder grade thing is currently hanging there, and not every landlord is thrilled about that even if you promise to put the old one back.
Check the dimmer compatibility before anything else, in the shop and again the day it arrives, because a fixture rated for one type of dimmer on a different circuit will buzz at low settings and nobody mentions this until you're living with it. Check the drop length against your actual ceiling height, not the showroom one, since six inches makes a bigger difference than it sounds like it should. And check the finish in your own light at home before you commit, because warm bulbs make brushed brass look different than the cool light in most stores, and I've seen people return a fixture they actually liked because they judged it under the wrong bulb.
Get the bulb temperature and the dimmer sorted before installation day, not after, and a fixture that felt a little plain in the box usually earns its keep once it's actually doing its job in a room you live in every day.