I have an extensive collection of ball pythons, but have more recently added boas--Tarahumaras, a Hogg Island, and Amaralis. I love them all. The Tarahumaras are a dwarf boa that I can keep in similar size tubs as my BPs. They are hissy as babies, but settle down quickly with handling. The Amaralis have the most interesting temperaments and are beautiful to handle. The Hogg is a sweetie and has an amazing peachy color.
Tarahumara
Hogg
Amarali
And, just for fun, if you are thinking of something out of the ordinary, this is a Solomon Island Ground Boa. Smaller than a ball python, a bit more feisty. Comes in beautiful colors.
Good luck in your search!