For a high value car that you have no intention of owning it has to be personal lease. You know exactly where you stand financially from day one. Deposit (up front cost) is generally low and provided you keep the car within mileage and well looked after it is hassle free. I quite like 2 year deals, likely to only require one oil change service and if driven carefully no requirement for tyres etc - C63 may be an exception here.
My 640d is my first lease and I will do it again. I have my eye on an E 220CDI AMG Sport Auto estate next at £280 ish per month if they are still around at the end of the year.