In case you've never had the pleasure I thought you might like to meet 'Twiggy', as in Ilex crenata 'Twiggy'. We have seen many posts discussing the problems of boxwood used in tightly sheared borders and knot gardens. Maybe this is an acceptable substitute.

Notice how dense the foliage is, it only has to be clipped once a year. Keep the bottom wider than the top so it doesn't get shaded out and lose foliage. PIX taken at public garden in Maryland.