My master's supervisor is a Chinese. He asked me to do PhD with him, but I said no. I want to go for another school. He then wrote me a PhD reference letter which ranks me middle. I think that is what I deserved. My another professor, who is a Canadian, also asked me to do PhD with him and I said no to him too. He then wrote me a letter ranked me top 1 and he referred me to the best professor in this field. My PhD supervisor told me that if you want a reference letter for your scholarship, please do not ask your chinese professor to do the reference letter!