Lease purchase will have unlimited mileage and the balloon will depend on the size of your initial deposit and monthly installments. small deposit & payments = big ballon.
For me, I prefer contract hire, still 100% tax and vat, but if you keep to a 3 year contract, you will never have a van that is out of warranty. as you all know after 3 years things tend to fall off vans especially if you do high mileage.