Seeing as I keep both species, and will continue to keep both species as long as I am in the hobby, I won't dissuade either.
Kings are easier as far as husbandry and feeding.
BPs are easier to handle since they are so darn slow by comparison, especially as juveniles.
The list of pros and cons will vary person to person.
It really comes down to which animal you want to care for for at least 15 years.