The thing nobody tells you about a lamp base is that you're buying a shape for the room, not just a thing to hold a bulb up. I noticed it about three months after bringing one home, walking past it at dusk before the shade was even lit, and realizing the silhouette of it against the wall was doing more for the corner than the light itself ever would. That's the part a shop can't show you under its own fluorescent lighting.
Where these go wrong is when people treat them as an afterthought to the shade, picking whatever's cheapest and skinniest because it'll be covered up anyway. It won't be, not really, not the bottom third of it, and a flimsy base will tip if a cat brushes past or a kid grabs the cord, so if you've got pets or small children underfoot, go heavier and wider at the foot than you think you need. They also don't suit every room on their own; a slim metal base can look a little lost on a big console table or next to a chunky sofa, and a bulbous ceramic one can crowd a small side table that's already got a coaster and a book on it. What they do sit well with is wood with some grain and age to it, a leather chair, linen curtains, anything with a bit of texture already in the room, since the base becomes another texture in that same conversation rather than a shiny intruder. In the shop, pick it up. A good one has real weight low down, the base should feel like it wants to stay on the table even before you've threaded the cord through. Check where the metal meets the ceramic or the wood meets the socket; a cheap glued joint will show a thin seam of adhesive if you look close, while a well made one is turned or fitted so the materials meet clean, almost like they grew together. Run a thumb over the finish too. A lacquer that feels tacky or a paint that scratches with a fingernail will look tired within a year.
Over time, the honest ones wear well. Brass dulls to something warmer and nobody minds, ceramic keeps its glaze as long as you dust it rather than scrub it, and wood just wants an occasional wipe with a dry cloth, nothing wet, nothing abrasive. Keep the cord away from where it gets yanked and check the socket connection once a year if you can be bothered, since that's usually where trouble starts, not in the base itself.
Put the right one on a table you already have and the whole corner finally looks finished, without you having moved another single thing in the room.