Boas are great! A common Colombian BCI are easy to care for, come in some awesome color morphs, and are generally puppy dog tame. Although they can get fairly large, and if you get a female you'll need a 6 x 2 x 2 cage someday, males stay a little smaller and can chill in a 4 x 2 their whole life. Or you can go for a Hogg Island, or say a Nicaraguan that stay smaller (nics stay about the size of a ball python).

Although I've noticed some Nics can have a bit of an attitude lol.