I support getting the snake you want the most. If well cared for, they can live a long time and you want to make sure it's the one you really wantYou have clearly done your research, set up and tested an appropriate enclosure before getting the animal, and overall approached getting a new pet in a responsible way. I think you'd do great as a BP owner, and of course if you run into any problems, our community is here to help.
When people say BPs aren't a great beginner snake I think that only applies if someone isn't going to put in the time and research for setting up a good enclosure and learning how to deal with typical ball python problems like their feeding. Since BPs don't naturally live outside of Africa, it takes a little more work to accurately simulate the environment there. Corns and kings are native to North America so they can be more forgiving of husbandry mistakes since their temperature and humidity requirements are closer to what is natural in most places in NA. It looks like you already have a good understanding of that though, so I think you'll be fine.
Congrats on being ready to bring home a new noodle, I can't wait to see your new pet!![]()