If my parents are US citizens and my sister is too, who should I choose go to sponsor my green card?
It will be somewhat faster through your parents but not by much.  YOu need to maintain your nonimmigrant status within the US at all times, regardless of who is going to act as a petitioner.  I cannot see how you are able to do that in H-4 status unless your spouse is a beneficiary of an employment-based immigrant visa petition, in which case you would probably be better off (faster) immigrating through your spouse than waiting for your parents' petition.