Unless you have far more research experience than clinical experience, it is almost always harder to get into an MD/PhD program than an MD only program.
I also question your maturity, if you're willing to base your decision to enter either program on something so trivial. Since your main interest is in clinical work, a PhD makes no sense. (The financial benefits are highly overrated.) You do realize you're talking about staying in school four years longer than you need to, just for what? A higher ranked school? That's crazy.