You posted the first post two years ago, I guess it is not easy!!

From my point of view (dealer) you should priorize the service. I've seen some companies force their plants to buy an specific brand, with great savings at the beginning. But later on, they have a worse service wich can mean significant less productivity.
Other times, the new service is much more expensive, and at the end there's no cost saving.
I have also seen problems with rentals, plants with rented machines with such a bad service, that they have to rent new machines, having the machines doubled.

The best case, and the easiest, is when buying from a central position a brand wich doesn't force plants to change their dealer. (One dealer sells and others repair)

A very good practice is to buy/rent very common or standard forklifts. If you have ten forklifts in a plant, and they all have the same characteristics (brand, engine, weight, height...), the service should be faster and cheaper, because the dealer will be very prepared (equipment, spare parts, workers...). It will also help productivity, because any forklift can replace another one: no drastic stops.

Hope it helps