Bro, earnestly speaking, I would want to opt for ijarah any time than conventional leasing as it's nothing but like taking personal loan on interest, both are islamically impermissible. Some major differences between ijarah and conventional leasing are as follows:
1. In ijarah, they will begin charging you the rent after one month of delivery of car, where as in conventional leasing, they charge you interest from the next month, no matter when the car is delivered.
2. In ijarah, your monthly rental will immediately be stopped, if the car is stolen, lost, destroyed, or otherwise not worthy of being used, where as in conventional leasing, you would continuously be required to pay the rentals unless insurance claim is settled.
3. In ijarah, if you miss out on any rental on time, you won't be charged interest, where as in conventional leasing, if you miss out on any rental, you would be charged interest.
4. In ijarah, if the customer dies, the legal nominee can seek title of car by just paying the outstanding principal amount only, where as in conventional leasing, legal nominee would be required to pay the outstanding principal plus markup in order to transfer ownership.
These four differences should be kept in mind, if one opts to go for ijarah.
PS: I do know ijarah in itself contains many flaws which may not be acceptable islamically, but it at least is a positive initiative towards interest free financial system.