Large, congrats on getting a ball python. They are my favorite reptile ever and I'm glad you are getting a chance to enjoy them too.
I know you didn't ask for it, but I'm throwing you some advice anyway:
Watch your temperatures and humidity levels VERY closely with your ball python. Ball pythons are MUCH more sensitive to sub-par conditions than some of the other reptiles that you've been through in the last year. Ball pythons get sick much easier, go off of food, have bad sheds, etc when their conditions aren't exactly right. I'm not saying they are HARD to take care of, but they are definitely more sensitive to husbandry errors.
Your snake looks like its in shed. Shedding is a great indicator to you of whether or not the humidity is right. If he sheds in one piece and leaves a little ball of rolled up skin, your humidity is good. If he sheds in flakes and little pieces that stick all over him, your humidity is too low.
Just offering my unsolicited advice. I hope you can have success with this species and not get rid of him in a couple of months like the others...