Compared to the most recent seasons of BBUSA, I'd give it to BBCan, mainly because they've for the most part produced 2 solid casts. Especially the BBCan2 cast.
As much as I love BBUSA (I live in the US so I grew up on it), BBCAN season one had Alec and Peter, and Two had like... everybody. Really great show every episode while BBUSA has off moments.