There isn't really any competition, but it has little to do with the bike-sharing system and everything to do with the host city. While Montréal seems French in so many ways, it's actually a closeted Dutch city, where biking has become so popular and so mundane that driving almost plays second fiddle. Lots of people use Bixi to get around, but even more appear to have their own bikes and to ride them everywhere. The following video is characteristic - or possible an under-sampling - of the biking scene in the city.
I took this video at 8 AM from our private terrace at L'Auberge de la Fontaine, in the Plateau Mont Royal neighborhood. (The stress of planning and executing a wedding melted away as soon as we arrived at this hotel, the perfect honeymoon home-away-from-home.) After biking the entire length of this bikes-only, protected path later in the day (see map below), Maggie and I only confirmed what we first suspected when I made this video in the morning: we need to move to Montreal.