Welcome to the forum Sugar. It's wonderful you are taking your time and gathering your information before deciding which type of snake would best suit you.

We have both ball pythons and BCI's (which I've seen referred to as columbian boa's or common boa's in the pet trade). They are both wonderful snakes but each have unique care requirements (we have caresheets available here for both). There are a number of boa species that don't grow overly large and are wonderful snakes to have. We have members here with male BCI's that are topping out at only around 4.5 to 5 feet and some like the male we are fostering that are over 6 feet and probably not quite done growing yet. Females like Jamie Glass have get considerably bigger. They are also very strong and pretty thick bodied but generally if handled properly when young, a very laid back snake temperment wise.

Have a good look through the threads here on both ball pythons and boa's and you should see a lot of pictures and a lot of real experience to draw from. Please consider using a breeder rather than a pet store for your purchase as you're likely to get a much better young snake that is an established eater, is healthy, is captive born and is of a quaranteed sex (especially important with BCI's as the females can get much larger).

Feel free to ask tons of questions. We are blessed to have not only wonderful owners of many different kinds of snakes here but also some top notch breeders of both ball pythons and boa's.