My lovely girlfriend "Ella" and I will be getting married soon. We want to visit my family in America. (United States) She is Chinese and already has her passport.

What is the best visa for her to get.

What is her purposes in coming to the U.S. (visiting? Immigrating?) What is your status?

just visiting,
I am living in China on a Z visa, with a residence permit. with no real plans on returning except for holiday.

For visiting, tourist visa (B2 or B1/B2) is appropriate. However, if you are a U.S. citizen, and she is married to you (or maybe even if they find out you're her boyfriend), there's a good chance of denial for immigrant intent. If that happens, the only other way for her to get to the U.S. is to apply for a green card.