i'm not sure how nw/as prices ex-yvr, but if good, i suggest you go with as.

sq is a terrible option because connecting in sin en route to china isn't too cool.

i'd also be inclined to strike asiamiles (cx, mu, jl) for the same reason were it not for the fact that mu flies yvr-pvg daily. but, given your travel patterns, i'd advise you to steer clear of asiamilers anyway.