My opinion on ball pythons: If you don't want something that can take off (as a baby) with no notice, LOL, a ball python is still a nice pet. They're just a little more meticulate, so to speak, about their requirements: two identical, tight-fitting hides (one for warm side, one for cool), low nineties for their warm side, low eighties for their cool side, 50-60% humidity at all times unless in shed. Below 80 or so is bad for ball pythons (respiratory infections can occur), meaning you'll probably need two heat pads (one set to 80ish, one set to 90ish) to keep the temperatures up. If those basic needs aren't met, the snake can, and possibly will, go off feed until the issues are corrected. All that aside, they still make awesome first pets. The setup isn't really much to take care of once you have it all setup, providing you use thermostats and not lamp dimmers, which I don't really recommend for ball pythons because of the fluctuation in temperatures that results from using them. It's very fun to handle them once their used to you... they are full of personality, and I love handling something bigger than a corn snake, LOL. It's also a plus that they don't move very fast. Although, depending on the individual's shyness, they are over-handled and sent off feed easier than a corn snake.
My opinion on corn snakes: They are dirt easy to take care of! Dimmers are better used for these snakes than for ball pythons, in my opinion. My only gripe with them is that they can be a little nippy as hatchlings and move VERY fast. I had one get away from me and go under the bed. Took an hour to get him out.
Either snake is great as a beginner as long as you meet their basic needs.