I'm surprised that Santa Barbara, CA didn't make this list. The bicycle freeways there are amazing. I'd have to say that SB has the edge on Basel, having biked in both cities. SB has the advantage that you aren't sharing the road as much as in Basel.

That said, the bicycle routes here in Switzerland are great. They're well marked and mostly safe. There are however, some pretty dangerous crossings and roundabouts that have to be negotiated at times.

Portland might be okay for cycling, but the rest of the NW isn't particularly good. Seattle's downright frightening outside of the major bike paths like the Burke-Gilman. And when you get out to the countryside in most of the US, cycling is pretty dangerous, when compared to Switzerland.