No, the position is more complex than that. Your original question isn't answerable in that form, it depends on the design brief and motor type among other things.
The 1500 watt can be a little faster and have a little more torque combined, or it could be just faster or just more torquey than in the balanced form of partially gaining torque and speed.
If you specify the type of motor that makes the question a bit more answerable, but the best way to approach this question is to state what your requirements are. Then the best type and spec can be recommended.
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My only point of reference is my Cyclamatic CX1 and there are NO bike shops in the area where I can test-ride e-bikes.
My requirements are as follows:
a) ~30mph top speed
b) better torque than the Cyclamatic CX1
c) the greater the range, the better
I ask myself, why should I get a cyclotricity stealth 1000w for 1200 pounds instead of buying:
a) 1000w conversion kit off ebay (~200 pounds)
b) 60v/20ah battery with charger from Aliexpress (~500 pounds)
c) Some random, albeit compatible, bike from Halfords (~200 pounds)
d) Pay someone to put everything together since I can't do it myself
Does this not make sense?