If you're standing in a showroom running your hand along the mantel, the first thing I'd tell you is to think about the wall it's going against, not the fireplace itself. A fireplace only looks right in context, and a lot of them get bought because they looked good under showroom lighting and then arrive home to a wall that's too small, too dark, or already busy with a window and a radiator fighting for the same few feet.
When you're actually choosing one, check the finish in daylight as well as under the shop's spotlights, because a stone surround that looks warm and pale at ten in the morning can look gray and flat by evening, and you want to know that before it's bolted to your wall. Check the depth of the thing too, not just the width, because a lot of people measure across and forget that fire surrounds eat into a room more than you'd expect once skirting boards and hearth stones are added. On delivery day, look at the hearth edges and the inside of the firebox for chips, since that's where damage hides and where it's hardest to argue about later. Where a fireplace stops making sense is in a small rented flat with a shallow chimney breast or no flue at all, where an electric insert pretending to be the real thing ends up looking like exactly that, a pretense, and you'd be better off with a simple stove-effect heater that doesn't try so hard. It also clashes badly with a room that's already got a strong architectural feature doing the heavy lifting, a big bay window or an open staircase, because two focal points fighting for attention makes a living room feel unsettled rather than grand. A fireplace earns its keep most in a room with low afternoon light in winter, where the glow actually does something, rather than a bright south facing room where it just sits there unlit for most of the year looking like furniture. Over time, stone and brick surrounds age well and genuinely improve, picking up a bit of soot and character that suits an older house, while painted wood surrounds need repainting every few years if they're anywhere near actual flame, since heat yellows white paint faster than anyone expects. Cast iron needs a light coat of grate polish now and then to stop it looking tired, and marble needs nothing except a damp cloth and the restraint not to scrub at the veining when it stains.
If I were choosing today, I'd start with a honed limestone surround in a pale gray. It takes the light well morning and evening, and it doesn't shout over everything else in the room.