I suggest you take some time to look at this list from the Residency Match that was just held last Friday (March 19th). Overall, US MD seniors match rate was 92.8%, and US DO seniors match rate was 89.1%, so not a lot of difference, but if one looks at the specialties there are several significant differences. If you have a specialty in mind you can look to see if DO is fine or not - though keep in mind that many change their minds about specialties once they get into rotations and fully see their options.
Then you have to weigh the fact that getting into med school is tough overall - fewer than half make it in. A guaranteed option is tempting. I know many students who went to DO schools who are happily doctors now. If you are pretty sure you want something like Internal or Family Med, it would be hard to turn down the guarantee IMO.