If you do your homework and choose the right leasing deal, then it is not impossible that leasing can work out cheaper than cash. But this isn't always the case, and it does give less flexibility than owning the vehicle. So you need to understand exactly what your requirements are before you sign up.
Personally, if the total amount payable works out exactly the same between 6 or 9 months upfront, i'd go for the lower upfront payment. Hang on to your money for as long as you can. But really only you knows what you are comfortable with.