A print is the cheapest way to make a room feel like it belongs to you, and most people spend all their money on the sofa and none on what goes above it, which is backwards. The wall is free real estate. Fill it with something that actually means something to look at, not the thing that came in a frame from the clearance aisle because it matched the curtains.
Color is where this gets decided fast. If you already own a lot of pattern or a loud rug, go for a print with one dominant color that echoes something else in the room, a single thread pulling it together rather than fighting for attention. If your walls are still working out what they want to be, a print with warmth in it, rust, ochre, a deep plum, does more for a room than another gray abstract ever will, because gray on gray on gray is how living rooms end up looking like hotel lobbies nobody chose. If you own nothing yet, start with one piece that has a strong focal point, a face, a shape, a clear subject, not something so abstract it reads as wallpaper from across the room. You want something your eye actually lands on. When you're buying, check the edges before anything else. Run a finger along the frame corners, check they're mitered clean and not just glued and hoping. Hold it up to a window if you can, cheap paper shows through, good paper has a bit of weight and doesn't bow in the middle when you tilt it. Check the glazing isn't the flimsy plastic that scratches if you look at it wrong, and check the hanging hardware is actually screwed in, not stapled to cardboard backing, because that's the thing that fails at month four, not year four.
A well made print uses proper pigment ink that won't fade in a sunny window within a year, printed on paper or canvas with real texture to it, mounted square, framed with a joint that doesn't show daylight through the corner. A disappointing one looks fine in the box and then three months in the color's gone flat, the corner's lifted, and you're explaining to a client who asked about it that it used to look better. I've had both. The flat one is in a drawer. The good one's still up.
Next to it I'd put a lamp with a warm bulb, something that throws light up and across the print rather than a cold overhead that flattens the whole thing into a photocopy of itself.