Wow, can't believe I've never added to this. I can't think of 10 that have really made a difference, but a few have made a HUGE difference.
1. On board air. Good for so many things
2. Solar
3. 25 gallon water tank upgraded from 7
4. 45 gallon fuel tank upgraded from 30
5. Fixed ladder
6. Awning, in my case a CVT awning
7. LED bulbs throughout
8. Trasharoo. I wish I could fit two of them.
Good for storing everything you don't want in the van.