1. I like the simplicity of the BBUS house.
2. BB:CAN house lacks privacy and is hard to scheme and plot in, lots of wide open areas, it seems you can see pretty much the entire house from the kitchen area (other than the bedrooms). BBUS house on the other hand provides tons of (semi)private areas to scheme and plot.
3. The fact that the BBUS house is a bit of a dump (esp when the annual ant infestation kicks in) adds to the charm of the show