楼主自己就读的学校听上去不错。我的建议,留在本校。国际学生念PhD,除了考虑排名外,还得考虑你在这个项目中的位置。说明白点,就是faculty会不会拿你当回事儿,会不会真的care about you。如果faculty对你重视,对你以后找faculty职位是有利的。所以,一个熟悉的环境下念PhD,会是非常不错的。
keilvinleihuang is right! You can access to more information, save much time, and start research asap. No need to adapt to a new enviornment, unless you can ensure the new school is better than the current one.