If you're in a position to publish in any of the Nature titles, during your PhD then you'll be very fortunate. The Nature Reviews journals only publish review articles, which are usually written by established leaders in their field, bringing together all the relevant research in a particular field.
What matters with a journal is the 'Impact Factor'. Nature Genetics has the highest impact factor of all genetics Journals (29 in 2004). Nature itself has the an impact factor of 32 - making it the highest of any multidisciplinary science journal. In other words a Nature paper would be more impressive.