Pick up a piece before you buy a set, because the weight is the thing that fools people online. A fork can look identical to another fork in a photo and feel completely different in your hand, one solid and satisfying and the other light enough that you wonder if it will bend under a piece of steak. You want the heft that feels a little expensive, even when it wasn't, because that's what makes a set feel worth keeping instead of something you're already planning to replace in three years.
Finish matters more than pattern, honestly. Plain stainless in a matte or brushed finish is the easiest thing to live with, it hides water spots, hides scratches, and doesn't scream at you when you mix it with whatever plates you already own. Mirror polished looks sharp in a drawer but shows every fingerprint and every tiny scratch within a month, so unless you enjoy polishing cutlery before dinner, I'd skip it. Gold and copper tones are lovely for a few pieces mixed in, less lovely as an everyday set, they scratch visibly and look tired fast if they're going through a dishwasher twice a day. Where flatware falls down is anything with a lot of texture or an uneven surface, because food gets stuck in the grooves and no amount of scrubbing gets it fully clean, which is a bad trade for something that looks nice on a shelf for about a week.
For sizing, it's less about inches and more about weight and balance, but there are numbers worth knowing. Dinner forks usually sit around seven and a half inches, teaspoons closer to six, and if a set feels oddly short or long compared to flatware you've used before, that's often a sign it's cheap stamped metal rather than properly weighted. Hold a fork by the very end, let it balance across one finger, if it tips hard toward the head it's going to feel off every single time you eat with it. For a household of four, a five piece setting times eight gives you breathing room for guests without buying a drawer organizer the size of a filing cabinet, which is the real mistake people make, buying a huge set for a drawer that was never built for it.
So before I buy, I ask myself one thing standing there holding the fork: would I actually want to eat dinner with this every night, or does it just look good sitting still?