As everyone says, whatever suits you. Personally PCP works for me. 2k down in 2016 for a brand new mk7. All the benefits of a new car, monthlies I was happy with. 2019, used the equity in the mk7 plus another VW contribution and £500 from me for another brand new 7.5. Again all the benefits of new and monthlies I was happy with. For a lease, the monthlies will be cheaper but I don't like the idea of trying to find 2-2.5k every couple of years to sign up to a new lease deal.
At least with a prestige motor, depreciation won't be so bad. Therefore at the end of a PCP you should have money to put into a new motor.
Personal loan is defo the cheapest way but when you try and borrow 25k plus, interest goes up, therfore the monthlies will be similar to a PCP and you will still own an older car once its paid off, which probably won't be worth that much. It will be out of warranty in the time you own it, you'll have to wait for new models etc if you want to own it outright. At least with PCP you can change quite often.
Anyway, just my thoughts.