If cost is your main concern, buying is always better than leasing. This assumes you are buying something that doesn't have a catastrophic weakness.
If cost is no object, then yeah, leasing a new car every 3 years is solid. You get something new all the time. You rarely have to deal with maintenance. My biggest issue with leasing is the mileage limits. For my primary car, we put about 18K-20K a year. That really makes lease prices unattractive, and also the process is also annoying. You essentially are trying to predict how many miles you need before you need it, and the penalties are unattractive. Also at those mileages, you can't get away having to do tires & brakes in the lease period.