Correct me if I'm wrong but it's sounding like you'd rather have the boa. And when it comes down to it, the "best" beginner snake is the one you will enjoy most (within reason of course). As Vyprz said, it's definitely worth doing some research on the various subspecies and locales to see what's out there. But if you want a boa... get a boa.
I don't know what I want personally lol But I think I'm gonna go with the BP to start off, and later on I'll get he boa, to make this whole thread complete.
"I have no fear of losing my life - if I have to save a koala or a crocodile or a kangaroo or a snake, mate, I will save it."
~Steve Irwin-