Our experts took three staples of a woman's wardrobe—blazers, cotton slacks, and cotton shirts—from Ann Taylor, Banana Republic, H&M, J. Crew, and Talbot's, and did what consumers can't do before buying: They tore out seams, peeked under linings, ran the clothes through a washer and dryer (the blazers were dry-cleaned), then checked stitching and looked for pilling, fading, and loose buttons.

Two surprises: H&M, known for low prices, did better than you might expect, adding high-end details, but Talbot's took some shortcuts (for instance, its blazer lacked piped lining, which all the others had). The winners:

Best shirt Banana Republic, $58. It had smooth, strong seams; thicker fabric for better drape; and a double-lined yoke to make the shoulders sturdier.

Best slacks Banana Republic, $68. They had neat finishing, deep hems that would be easy to adjust, and tight stitching on the seams. (On any clothing, count the stitches per inch; more than nine is good.) Talbot's slacks were a close second, but they had rolled hems, which would be harder to adjust.

Best blazers Ann Taylor, $228; J. Crew, $238. Both are wool. (Ann Taylor's, which is pictured, has a bit of spandex that should help maintain shape.) Both draped nicely and were easy to care for; wrinkles came out just from hanging them up. J. Crew's had an inside pocket with a separate pen pocket and interfacing, a layer of extra fabric that's usually only in collars, shoulders, and pocket flaps.