Size
Board size / platform controls the comfort and feel of your board. Smaller board will carve better, but is less stable. Larger boards are more stable and have more power margin to protect it.
Range
How far and long your board can go before needing to charge, lots of factors go into this, but it's possible to get a good estimate going into it.
Power
With more power your board will be more responsive to inputs and have a larger safety margin when riding unpredictable terrain.