1. Stand-up counter balanced electric tend to be max lift capacity limited - commonly less tthan 5K basic lift capacity. A few manufactuers offer a 5K capacity but the unit get to be very long.
2. A 3 wheel (most actually 4 wheel w/ tandem steering tires in lieu of a single steer) is a nice alternative to a stand-up or 4 wheel counterbalance as most operators can step to the ground from a seated position which makes it suitable for frequent on/off operations & gives the operator soem in teh seat time while traveling. Again capacity is limited - most are 4K lift capacity - there is one company that has a 5K but the ground to seat height is higher than most due to the height of the battery compartment.
3. If you decide to go to a stand-up or 3 wheel make certain you get a battery w/the largest kWh rating - this will give you more run time between battery charges. The battery compartments are smaller than a 4 wheel electric - which simply means they can hold a larger kWh rated battery.
Some folks will talk about battery size in terms of amp/hr size - all this means is the rated discharge rate over a 6 hr (some brands for Europe or Asian countries will use a 5 hr rating.) In my simple mind - amps (resistance to flow) equals heat and amp hr ratings have little to do with run time and kWh is equal to power (energy) has every thing to do with run time on a single battery charge.
I am from a simple sales & marketing back ground and like to reduce all that technical jargon down to an understandable level and if you want to know all that stuff I'm certain someone can explain it all but get a big cup of coffe or two and a nice easy chair with a remote handy for the flat panel TV.

So I get out of hot water with all these "service engineers" - I will say when it comes to properly repairing and/or trouble shooting or suggesting option to resolve operational issues you need to understand the details of that stuff.
Just my 2.5 cents worth.