As a longtime luggage reviewer, I have a somewhat unconscious habit of casually surveying crowded airports to note the kinds of bags people are using as they travel. And over the past decade, the rising preference for hard-sided luggage is undeniable.Hard-sided luggage looks good. It’s sleek and modern, with a reassuringly minimal exterior (the so-called shell) that, in both name and style, evokes a kind of armor against the world.But hard-sided luggage is not always the best tool for the job.Unlike soft-sided bags, hard-shell suitcases won’t squeeze into tight spaces or flex around last-minute souvenirs. They can crack under pressure (literally) and show scratches like a badge of honor (or shame).Still, when it’s done well, hard-sided luggage does offer real advantages to certain people who find these bags easier to maneuver (due to their rigidity), and they’re also a snap to clean. Over the past several years, we’ve tested more than 40 pieces of hard-sided luggage. We’ve rolled them through terminals, scraped them on subway turnstiles, and checked them on long-haul, multi-leg flights (which often involve mysterious luggage mishaps).The models we recommend strike the best balance of durability, design, maneuverability, and price. They’re not perfect for every traveler or for every trip, but when you need a suitcase that retains its shape and keeps your stuff safe, these are the bags we trust: a classic all-around pick, an upgraded pick with some refined styling, a good lower-priced option, a carry-on with locking wheels, and a carry-on reinforced by aluminum framing.