Yup, that is a tough question. When I first got into snakes I had to make this choice. It took me about a week to make my decision: ball python. I just really like their personalities. They are also very unlikely to bite so I like that (I am not saying that corns are out to get you though, they can be quite sociable). I also like the their coloration. I don't know what it is about them, they will always be my "first love". One of the other reasons that I went with a bp is that I was going to be on a three day road trip in about 6 months and I wanted something that would not get as stressed out.
I like corns though. I just picked up a "snow" corn. I really like her. They are pretty active but I have found that bps and corns are pretty secretive durring the day time. One of my favorite things about corns is that they have a GREAT feeding response! My little girl has never refused a meal, if you have ever experienced a bp (or any snake for that matter) that won't eat, you know how frustrating it can be. That is really the only reason that I can think of why a corn may be a better choice. If you get a snake from a local shop, ask if you can see it feed, if you can see it feed you are good to go.
Listen to the person you are talking to also. Do a lot of research first then ask the person a whole bunch of basic questions. If they know what they are talking about, you are in luck, chances are the snakes are in good hands.
One more thing on corns and bps: which are you more comfortable handling-more of a skiny snake or one that has a larger body mass?
Have fun, post some pics of what you get!!
