You could go for the smoked quail and date appetizer. You could go for the now-famous undulating wood ceiling. But the best reason to go to Banq is to simply sit, and watch the social hopefuls preen. When the French-Asian fusion spot made its debut in the South End this winter, boldfacers came from far and wide. These days, Banq still draws its share of top chefs, fashion insiders, and media darlings—who cluster around the low-lit tables, sipping Collalbrigo prosecco and air-kissing passing acquaintances—but the dressed-to-the-nines newcomers looking to hobnob are themselves the best show on all of Washington Street.