If the vehicle has to be specific, then leasing may make the most sense. The vehicle is an operating expense, and you get the right vehicle for your needs. As you noted, the leasing company owns the vehicle. The lease is effectively a long-term rental.
In my case, a "lightly" used U-Haul box truck was the answer. I was able to buy a 2008 Ford E-450 from U-Haul with about 140k miles for just under $10k all in. It's clean and runs like a champ. The cab design hasn't changed in 18 years, so it doesn't look dated.
In the year I have owned it, I have driven almost 25K miles. I have replaced a tire and the tie rod ends. It is about to get two more tires. Otherwise, the only expenses have been insurance and registration, fuel and routine maintenance.
I have modified the box by adding an RV door and steps on the side, so I am not always going in through the rear roll-up door. Plenty of room inside for my packout stacks, ladders and saws, and still room for job supplies like lumber, drywall and plywood.
It is about the same length as an extended Transit, but a bit wider and taller. It handles surprisingly well.
The biggest downside; it hasn't seen a gas pump it doesn't like. 8 mpg is tough at $5.00 a gallon.
I had given thought to leasing a van. With a $1300 lease payment, the U-Haul would be paid off in 8 months. That leaves a lot left over for fuel and, more importantly, funds to redirect into the business. If the truck suddenly tanks, it would be easy enough to send it off to the scrap yard without shedding a tear and get another one. Again with the 60 month, $1300 lease payment, I could buy 7 U-Hauls.
In my case, I can adapt the truck to my needs. But if the needs are specific, leasing a purpose built truck makes sense.
