Whatever you decide to go for, if the plant is to provide some privacy screening, it needs to be an evergreen so you don't end up looking at a bunch of bare twigs during the dormant months. To help narrow things down, you need to determine what the light and soil conditions are so you can choose a suitable plant for the position you want it to grow in. You might also want to consider whether you want flowers/scent, and/or autumnal interest such as berries. Also, pay attention to its predicted maximum height/spread, and rate of growth.