My neighbour planted leylandii. It now needs cutting twice a year to keep it to 11 feet, which I need to pay for. He planted it hard up against the boundary rather than leave access space to it on his side. So I can't build any sort of screen without giving up a strip of my garden. All of the plants along the base suffer from trampling due to the cutting operation.

As well as being dark green, Leylandii leaves don't reflect light. Deep shade persists at its base until mid afternoon. All of the shrubs that I grew previously along that boundary have died or are dying from starvation and light deficiency. I've had to move my greenhouse. We can now no longer see the sky from our living room. We now no longer sit out on that side of the house becase of the oppressive feel.

How about a nice beech hedge, planted so as to be fully maintainable from your property?