The thing nobody tells you about metal coffee tables is that the base matters more than the top. A thin tube frame will wobble every time you set a mug down with any force, and you'll spend two years thinking it's just how these tables are. It's not. Pick one up before you buy it if you can, or at least read enough reviews to know if people complain about movement. A solid, welded base should feel almost bolted to the floor.
A metal coffee table sits well against things with some softness to balance it out, a linen sofa, a wool rug underneath, even just a stack of worn paperbacks on top to take the edge off. Pair it with another hard, cold surface, say a glass dining table in the same room, and the whole space starts to feel like a waiting room rather than somewhere you'd put your feet up. For finishes, I've found the ones with a matte black or aged bronze powder coat live with almost anything and don't show every fingerprint and water ring the way a bright chrome or brushed steel top does. Brass looks incredible in photos and shows every single thing in real life, I learned that one the hard way with a table that looked like a crime scene of coffee cup rings within a month. If you want shine, get it in a finish with some texture to it, not a mirror polish.
Measuring is where most people get it wrong, and it's an easy fix. You want about 14 to 18 inches between the front of your sofa and the edge of the table, enough room to get your legs past without doing a little shuffle every time you stand up. The top of the table should sit around the same height as your sofa cushion, give or take an inch or two, a few inches lower is fine and often looks better, but a table that's noticeably taller than your seat cushion will make the whole room feel off balance, like the furniture is arguing with itself. Length wise, aim for the table to be about two thirds the length of your sofa, not the full length, a table that runs the entire width looks like it's trying too hard.
Before you commit, measure the actual walking path around the table too, not just the gap to the sofa, because a metal frame with sharp corners is a different experience to bruise your shin on than a soft upholstered one.