Which is better, Mercer Consulting or Aon Hewitt Consulting Beijing Branch?

I am a management consultant. To tell the truth, these two consulting companies are both famous for their human resources, but it is hard to say which one is better. Mercer has a longer history than Hewitt and is more famous in the field of human resources, but the latter is not bad and has stronger strength. From our consulting point of view, both are similar. The key is to see who and what team will do it and give you advice.