Look, I'll stick to facts here...
I don't know what's the temperament of the ground Boas, but I can vouch for the BCI's, they are simply terrific animals to handle.
Many Candoias are WC, they are not too easy to breed, and there are alot of WC out there to be bought from whole-salers, so make sure you get one that is CB
I prefer BCI's by a long shot, they are the perfect combo of size, shape and color(especially Hogg Isle)
Also, you have a deal more options to go with BCI's... morph-wise. The Candoias are still "young" in the field and there aren't any morphs. Currently, many are still struggling with successfully breeding them.
BCI all the way, but I am a BCI lunatic so.... I am biased