If your work would involve complex non-linear analysis, then you should seriously consider using either Ansys or Abaqus, as these are generally accepted as the best solvers for this work. For example, contact analysis in Nastran (of any flavour) was possible using the CGAP element, but this is really limited to a non-sliding contact. To overcome the limitations of the CGAP element, MSC have recently introduced a more general contact capability which actually calls up the Marc solver in the background! NX/Nastran does something very similar and calls up the Adina solver, whilst NE have truly incorporated a general contact capability into their version of Nastran.
Sorry, but I really have to disagree with you on your statement "choosing one based on which pre/post processor I know isn't a factor". It is a factor, a very big factor, especially these days, where a lot of FEA being done uses CAD embedded systems, which are very very easy to use (IMHO too darn easy!), and as a result people are running analyses, who simply shouldn't be! My point being, everyone expects a relatively easy to follow, easy to learn, intuitive windows interface. I need say no more.