To get good answers, you need to be able to formulate a better question.
The performance bottleneck has to be in one of the three.
IMO better to get a controller that will easily handle as much volts & amps as you imagine you will ever need.
Weight and volume and price are limiting factors, so if you are noobishly starting out testing stuff, maybe pre-order the right size Nucular now, very long wait but free
and get a limited cheap one for in the meantime
The ability to adjust Maximum Battery Amps will protect your (bottleneck) pack from getting murdered. Or add a CAv3 to the mix.
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The more power you want, especially torque for big loads fast acceleration heavier loads and steeper/longer hills,
the bigger and heavier your motor needs to be, so that dictates your limits there
ignore the wattage ratings, heat really becomes the limiting factor there
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A top notch battery pack is very expensive, but do not skimp or you're wasting money.
Forget lead, top rated LI cells with decent longevty only, 3.6-3.7V nominal, decide whether you need high power density or high energy density, can't get both.
Once you decide on your motor, top speed will dictate your system voltage, lower the better for economy, value and range , distance per Wh
To get lots of range the more Ah you want, but that requires more weight and space.