EMI is divided into symmetrical and asymmetrical, most symmetrical EMI is relatively high frequency, and asymmetrical EMI is relatively low frequency.

In a filter, common-mode choke is designed to attenuate asymmetrical EMI, and differencial-mode is designed to attenuate both symmetrical and asymmetrical EMI.

However, as the increase of amperage requirement, the cost of differencial-mode choke are getting more and more than common-mode choke, the whole size of filter is also much larger.

So we should select filters based on the actual requirement, rather than "all the best" !(Ignore it if you are from Dubai...)