I don't think that it's a fair question, since it cannot be done without significant "fillers". But if it was done, I would trade Nash for Lowry (pretty sure, Toronto would be happy to do it).
The question to me is really, who is the best player in the trade, Rondo or Bynum? Right now, I would say Rondo, but it is very close. Both are cornerstones on contending teams, but Rondo has the edge because he is so competitive, and has taken his team further last season. Plus he seems to learn more from his mistakes, than Bynum does. But perhaps Bynum could use a change of scenery to reach his full potential.
Not to neglect Bynum's health issues, but he played all games in the regular season - except from his suspension, one game with a sprained ankle and one game of rest - and averaged 35+ minutes.