Rosy boas!! Rosy boas are IMO the ultimate starter snake. They dont get too large (usually max out around 3' or so), are forgiving in their husbandry, super temperaments, slow moving (unlike colubrids and even slower than most other boids), many different colours/patterns from black/white stripes to red/blue zigzag, its easier to leave them than other snakes if you go an a short ttrip sicne they dont require water daily (you can water them as little as once every 3 weeks, but i prefer to do it weekly), and tolerate handling better than any other snakes (except rubber boas, they are jsut as good as rosy's for handling).
I woudlnt recommend a Ball Python, as they have more exacting requirements than a cornsnake or rosy, do not tolerate excessive handling, and even CB ones may go off food which can be frustrating for a new snake owner.
Cornsnakes can be a good choice too. If you prefer colubrids I would reccomend that one. I presonally don't much care for colubrids. IMO they are fast, messy (sometimes), and unattractive. That's just my own personal preference though, you might like em