What other limitations do you have? How big of a home, commute/location, affordability, etc.
Do your kids already attend certain schools that you'd like to stick with? Or, perhaps you just like the idea of property values remaining stabled based on the schools.
The best schools in RRISD are not in Round Rock. So this becomes a little tricky! They are actually in North Austin.
I know these school districts very well (Round Rock & Leander) and would love the opportunity to help. I see your post is from awhile back.... let me know if you still need assistance.