I always like to recommend you go native. This means to see what plants are native to your area and grow the cultivated varieties of those that are sold at local nurseries. This means if pines grow native pick a member of the pine family or if cedar trees are native in your area a member of the cedar family. Native plants will have the best natural defense to local insect and disease problems. Your local extension service (contact the Master Gardener program in your area) will know what current insects or disease problems have been damaging privacy hedges in your area. Often a mix of plant material is best. Keep growing, Marianne Binetti