I'd suggest you look at Raymond since you are already running their order pickers. You did not specify if you are using them as dock trucks or in aisles or both. I suspect both, I'd look hard at Raymond Pacer models. It makes life a little easier for you with the same brand. The technician will already know your account, and your likes and dislikes. If you specify the same battery size as your orderpickers you can swap between units (The Raymond rep can help you withthis), and if you loose a battery you have the option of 'borrowing' from a less used piece of equipment.
Raymond is also offering their new trucks (both Pacer/Dock trucks and reach trucks in an 'AC' Model. This will give you longer battery life. If you are with a smaller company, with a fixed budget look at their newer pre owned equipment, and ensure that you get a good warranty that will last through your learning curve, and cover you for a while in your normal usage - at least 6 months.