Motor Mechanical Torque vs Motor Electrical Power
Motors are generally rated by their output, mechanical, power. So if you want to replace a 5 kW ACIM by a motor of any other type, then you should choose a 5 kW motor.
It may be that your load does not need 5 kW to drive it, and the original motor is over-sized. In which case you could investigate your load, find out what it does need, and then choose a smaller motor to provide just that.
Different types of motor are likely to have different efficiency, so will require different input electrical power to provide the same mechanical output power. At the 5 kW level, you could expect to find the efficiency differences to be fairly small.