Hi Andrew,
The Ultimate 2.0 is the most customizable and full-featured mBot available. It definitely has the most ability to grow with a young maker. The different controller doesn’t necessarily indicate that one is better than the other. The Ranger is a bit more user-friendly, but you will also be more limited in what you can do/create with the kit.
The Ranger is made for ages 8+ and the Ultimate kit for ages 12+.
I think that I would recommend the Ranger, simply because the complexity of the ultimate kit might be overwhelming and the Ranger still has a lot of options for adding on and growing as his skills increase.
Let me know if you have any other questions!
