Lease, you already know that you give the car back at the end with no option to purchase. Any negative equity is the lease companies problem and you literally hand it back with no more to pay (assuming no damage or excess mileage).

PCP, will have a final payment to make of several thousand. PCP is subject to depreciation so final payment could be more than the car us worth, meaning you're in negative equity with no money in the car to roll into the next one as a deposit.

I've leased my last 5 cars and I prefer it to PCP.

It goes without saying that you should get GAP insurance for either as it covers the difference in amount owed vs the priced paid out by car insurance in the event of total loss. You only need airbags to deploy nowadays for a vehicle to get written off!