Rocky Vista is starting from scratch. They are using a for-profit model, they are not affiliated with an already-established school, and there are people who can make a difference in your career who are skeptical. Right now, they are saying and doing all the right things, but in some people's eyes, it will take some time before they prove themselves.
RVU might very well end up being a great school, but Western COMP already is a great school. Say what you want about Pomona, or their school being in an old mall, but they've been doing things the right way for a long time, and they have produced some outstanding doctors. RVU has produced no doctors.
You can also get federal financial aid at Western. Don't underestimate how important this can be.
The doc who wrote my DO letter went to Western COMP. He is an attending ER doc at the busiest Level II trauma center in the country, and he is a total badass.