I’ll concur with a lot of the above, and from a personal note, I am going to especially second the Rosy 
Boa votes. We have been big (BI/Red Tail) boa keepers/breeders for many years and have recently gotten into Rosy Boas, and we are loving them, especially as beginner pets!
In fact, we’ve been doing some market research (to decide if we are going to expand into these) and so far we are getting great responses from families/beginners due to their size, and we are finding that they certainly have the personalities of the big boas, just packaged into these small bodies. We are now Rosy fans!
Here are some pictures of Rosies on another thread here on MM:
Hope this helps! 
Have fun with whatever you choose!