We put more importance on job perspective than immigration. But, what can you do by your chem- PhD? no offence. even though you Hai Gui, you can only get a lecturer position from a 211 university at best.
Vancouver is a tourism city, without much industry and research. Moreover, job outlook for Chem- or Bio- is very bad within the entire North America, except thousand years' old postdog.
personally suggest. if u r ambitious and want to Ni4 Xi2, pick Brown. Brown has a quite flexible polucy for course choosing. Once you get into Chem PhD @ Brown, choose CS courses as many as possible, and try to get a CS master's. Then every door is open to you. Above all, forget your chem- degree. It is a waste.
when you say sth, plz give this inexperienced guy a few examples to support your arguments. Have yo ever heard any Chemistry PhDs find a normal job outside the academia?