My suggetion is that go for one manufacturer who ever it will be. You'll find much easier to work with one partner and you can get more out of it as well. As somebody mentioned earlier small stock of wear parts that can stop your truck.
Be sure to take time when choosing right batteries and chargers. You can save a lot on long run. I do not know what you are used to use over there but I'd go for central watering system on batteries and HF chargers. I'd look also for battery fleet management. Check it up w.enersys-hawker.com/english/fleet_manag_1.asp?lang=e