All motors share some important characteristics

BLOG 004
The motors available for e-flight vary greatly in size and speed, but in some respects they are all remarkably similar.

Most motors [say, between 1oz and 10oz] can be described by the attached graph, which relates efficiency, power-to-weight, and speed.
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The efficiency curve mostly coincides with the %NLS line, but it falls below this line as no-load speed is approached. In discussions, unwarranted significance is often accorded to peak efficiency. Much more important is the efficiency at the actual operating speed. That efficiency varies little between comparable motors.
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The output power-to-weight values will differ between motors, but the shape of the curve is always similar. The peak always occurs at about 50% to 55% of NLS. This parameter is just as important as efficiency, but it is rarely [never?] mentioned in the motor guides.
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Peak efficiency [which occurs at about 85% to 90% of NLS] implies low battery weight, but it incurs high motor weight.

Peak output power-to-weight [which occurs at 50% to 55% of NLS] implies low motor weight, but it incurs high battery weight.

Neither of these peaks is a good operating point for typical models. The best compromise occurs at some intermediate %NLS value. This is demonstrated by my BLOG 002 "Power-to-weight ratio for the complete power train".