CR Magnetics supplies various turns ratios and core sizes for a multitude of applications. Which part is best really depends on what circuitry is connected to the secondary of the CT. Without more information, such as frequency, voltage required from the CT, and other requirements, we cannot describe the difference for you in your application. Both CTs are excellent products when used within their specifications. You might want to try and nail down exactly what signal you need from the CT to help decide which part is “best”.
We can tell you that the harmonic response from either of these CT’s is limited to 50 hZ to 2000 Khz in a linear fashion. This is a characteristic of the silicon steel core material. Silicon steel cores such as these are generally used in non-revenue grade applications which require higher output voltage capability. Our nickel core “-N” products are used in high accuracy, revenue grade applications and low level current sensing apps such as ground faults. Our high frequency ferrite “-F” products are used for high frequencies 10K and above. If your application is at the standard power frequencies of 50, 60 and 400 Hz, then you probably will be satisfied with a silicon steel core product.