I am very familiar with Rice, and just got a very nice offer from the business school. Here is my objective opinion:
The Jones School is still very young, but it is definitely an up-and-coming school and has put together a solid program. I don't think the US News ranking of 38 (?) comes close to doing it justice. Definitely seems like its strength is in placing people in banking/finance, particularly in Houston. Within Texas, the Rice brand alone carries a lot of weight. However, I don't think there is a question that, nationally, McCombs is viewed as the stronger, more prestigious program, and its admissions are more competitive. You can't go wrong with Rice though, particularly if you want to work in Texas.
I am still super anxious/nervous to hear back from McCombs, although the Rice offer will be tough to turn down.