Sand boas are far more forgiving in the humidity department ( which is responsible for a lot of RI problems newbies often encounter). They are also significantly smaller than a BP once they reach adulthood as 3skulls mentioned above.

Neither a KSB or a BP will be a real 'shower' until you take them out to handle, KSBs burrow while a healthy BP will normally just chill out in his hide for most of the day. Really just a matter of preference on that one.

Best of luck with whatever you decide to go for!