I have used a Honeywell current sensor based on Hall-Effect to measure current up to 100 Arms. LEM has also some similar transducers.

Siemens IL300 is an optocoupler that can be used for linear applications, but it requires some additional devices such as op-amps to build a valid circuit.

The current transformer can not measure DC currents, so be sure that there is no DC component in the current you want to determine. Hall effect devices do.