I’m sure this will be a popular answer, but if I had the option I’d jump into the Wizarding World at the first opportunity. J.K. Rowling created an amazing reality that I would love to take part in, and I know Ashley would be right behind me. I may be a bit old to be a first year, but I would gladly do my time and take the classes and learn how to survive in that world. It looks like a ton of fun.
One of the worlds I would try to avoid would be from a book I recently finished; Wolf by Wolf by Ryan Graudin. A fictional world ruled by the axis powers after they won the world war. That sounds awful and even though the people there might be interesting, I think I’d stay away.