I don't think Vancouver is worse than Seattle in terms of "druggies and street crime", it's just more concentrated and visible. Given the warm climate and concentration of social services, it's a bit of a magnet for transients from all over Canada.

Aside from that, I think you can attribute a lot of the differences to the simple fact that Vancouver doesn't have any highways going through it or anywhere near the downtown core.

I prefer it to San Fran, but given the 4 degree(C) weather with rain today, I can appreciate someone taking the opposing view.