Well just saying boa's vs pythons has an extremely large area of different sizes.
By what your saying you want I would deffinetly suggest a ball python. They dont get to big, but a good size, and 99.9 % of them are completely tame/calm. Ive never seen a ball bite unless you smell like a mouse/rat lol.
Also if you have the space and money to buy it, Id also suggest a type of boa constrictor. They are amazing, great feeding response, something ball's dont have (most of the time) and are also usually very calm snakes as a whole. My friend has two and they are both jsut great snakes but require a lot..big tanks and big meals as they grow.