Snake suggestions?

[Himerosa]

Hi, I really want a snake and my mom said she would let me get one if I could afford it, so I was wondering what snake would be right for me. I took an animal science class for a year and chose a corn snake and a king snake to take care of. We learned how to feed snakes, normal behavior, snake life styles, how to clean their cages, etc. I was looking at Ball Pythons, Rainbow Boas and Green Tree Pythons, however I don't know if I am experienced for these or not. Any suggestions for snakes would be great, I just don't really want a corn snake or a king snake. We also have a rabbit and cats, so huge snakes would be a no-go. Also, average enclosure size for the snake you suggest would be great thanks c: