I'll have you know that I studied Leylandii for my final-year university research project, comparing the morphology of two of the eleven then-known clones with the parents, which are in different genera, Chamaecyparis and Cupressus. The fact that it's an intergeneric hybrid explains its extreme vigour. It's quite likely that I had a more intimate knowledge of Leyland Cypress than almost anyone else at the time. It has a bad name for sure, and I hate to see it used as hedging, but if allowed to grow into a free-standing tree (and it's very quick to grow big), it makes a pleasant specimen. As long as you have a large park.