Right off the top of my head in no particular order:
1. Play with friends
2. Play in front of family
3. Decision to serve a mission would be supported by coaches
4. Freedom: Rose has the most guard-friendly offense in the country. There would be no leash
5. Can make deep tournament runs with the talent BYU has in the pipeline
I have no inside info. My guess is he follows a Jabari-like path.