Usually those with fine-textured, evergreen foliage, and some shade tolerance, so the undersides of the artwork don't go bare so quickly.

Good candidates for your area, among those that I know:
Boxwood (Buxus sempervirens), Some Junipers (Juniperus species) with careful selective pruning, Yaupon (Ilex vomitoria) in warmer areas, Japanese Euonymus (E. japonicus) small-leaved forms, and some forms of Firethorn (Pyracantha species)

Other species that I am less familiar with:
Yew (Taxus species), Barberry (Berberis species), assorted Cotoneasters, and Boxleaf Honeysuckle (Lonicera nitida).

And privet is sometimes used too.

And maybe Hebe cupressoides 'Boughton Dome' for a small one to practise on . .

But of all those, yew and box are the best. Yew is slower to shape, but better for bigger subjects, and it is the aristocrat of clipped hedges. Box is easily obtained in small sizes and is a great starter plant. Phil

I noticed garden centres now sell ready made wire netting shapes such as rabbits to grow boxus through for shaping. The nearest I get is box balls or squares.