Between those two I'd say the 350z is probubly a little roomier. however I would look for a used Subaru Legacy 2.5GT Limited. It's roomy, good looking, packed with goodies, AWD, quick stock and easy to tinker with to get more juice out of.
Her's a few in youor price range:
http://www.usedcarsplus.com/usedcars...ted/index.html