Who should be the sponsor?

Both of my husband and I are in US. My husband is a PH.D studend with a RA Position. He is in his second year of the program, but has been in US for 6 years. He has an older brother who has a son in China. I have a fulltime accounting job for 2 years. My parents, sister and brother are all in China. We are going to invite my husband's parents/my parent in law to visit us soon. The question is whose invitation works better for passing the Visa interview. Thank you.