I wouldnt reccomend a ball python as a first snake. Yes they are nice looking, easy to handle and such. BUT, they are known to go off their food for long periods and can be worrying for first time keepers of snakes.
Bos on the other hand rarely go off their food and can be got it many dwarf forms, hogg island, sonoran dwartf, and a male colombian boa wil rarely get much bigger than 5 - 6 foot.