A dining room light works hardest in a low, square room with a table that gets used most nights, and it works least in a room so grand that one fixture looks lost in the middle of the ceiling. If your dining area is really a corner of the kitchen, or a table pushed against a window, think about scale before anything else. A pendant that would sing over a proper eight seater can look like it wandered in from a bigger house when it hangs over a table for four. Measure the table first, pick the light second, not the other way around.
If you have nothing at all, start with a single pendant, hung so the bottom sits roughly thirty inches above the table top, give or take depending on your ceiling height and how tall everyone in the house is. One good pendant in a warm metal or a glass that takes color well does more for a room than three small fittings trying to share the job. It sits well against a wood table with some grain still visible, against mismatched dining chairs that already have a personality of their own, and against a rug underneath with pattern in it, a faded terracotta or a deep blue, something that gives the eye somewhere to land besides the light itself. Where it struggles is a glass topped table with chrome legs and a pale floor, everything bouncing light around with nothing to settle on. Warm the room up first, then hang the light.
The difference between a pendant that feels special and one that feels thin shows up fast once you get hands on it. Lift the shade and check the weight, a cheap one feels hollow and tinny, a good one has some heft even in a slim profile. Look at where the flex meets the ceiling rose and where the shade meets the fitting, a clean soldered or properly fixed joint versus a visible seam with a blob of glue holding it together. Run a finger over any painted metal, a good finish feels smooth and even, a rushed one has texture where it shouldn't. Ask what bulb it takes and whether it's dimmable, because a dining room that can only do one brightness is a dining room that can only do one mood, and dinner needs at least two.
The best ones throw a particular kind of light onto a white tablecloth or a dark wood table, a warm pool in the middle with the edges of the room left soft, so the food looks better than it probably is and nobody notices you only cooked one course.