There’s a certain uniform you spot while walking through the Whitney Museum or grabbing coffee near Central Park in fall: a chic, beautifully cut sweater tossed over slim trousers or dark-wash jeans. The Upper East Side women wearing these kit tops probably paid top dollar, but you don’t have to . . . not when you know where to look. Fall sweater tops are already having a serious moment, and the good news is that the polished, put-together pieces trending uptown are hiding on Amazon this season. I pulled together 17 sweaters that deliver all-day comfort, work with what’s already in your closet...